Roman Insulae and the House of Diana: A Western Contemporary Perspective (Essay)

House of Diana, Ostia, ItalyIntroduction

Ancient Roman society maintained a steadfast orbit around its powerful leaders. These figures, owning incredible influence and authority, were larger than life in their time, and often deified after. Today, the story of their succession provides a political narrative accompanied and informed by archeological evidence. These physical remains, which tend to depict Roman life and governance, aid in the historical understanding of the ancient world and thus Western Civilization. The most studied architectural building types, or genres include the forum, temple, market hall, basilica, circus, theatre, bath house, mausoleum, and triumphal arch, which remain today as artifacts representing the political dynamics of the period and the human and material capital expended for construction. In addition to their role as forensic objects, the Roman ruins have profoundly shaped every aspect of Western Architecture, Engineering, City Planning and Design from their earliest days of service.

In Europe, Asia Minor, and The New World, the [physical] framework for civilization set out by the Romans informed urban planning, building design and construction, and a system of hierarchy for our built environment. Echoing Roman precedent (or in cities once under the Empire’s rule), buildings with monumental, civic, and religious purposes have since occupied the prominent nodes within an urban setting.

In contrast, domesticity has been [naturally] adapted to the subordinate acreage of a city, in “polite deference” (1) to those spaces which are communal. Obvious exceptions to this rule are the Roman palace, domus, and villa genres, which provided cues for subsequent elite classes to follow suit, often using extravagance and locale as their chief symbols of status. Still, the majority of Romans were not elite, senatory, nor even bourgeoisie, and like all civilized cities to follow, these middle and lower classes represented the undisputed majority, often by several orders of magnitude. It is the residential housing of this majority which will be examined in this study, since this genre is prone to scholars’ neglect as a building type – perhaps for its perfunctory or infrastructural nature – even as it may be the most important model for contemporary building today, especially as a world-wide exodus into cities gains momentum.

The Ancient Roman model for urban housing is the Insula, which translates roughly to “island” in English. Thus the urban island may be taken to mean a large multi-use block, featuring both residential apartment housing and commercial amenities. Using streets, it is segregated, or set apart from its neighbors, but permitted to engage in and contribute to a local context, promoting a coherent but heterogeneous distribution of urban land use. Following a casual and flexible format, it is unlike the large fora and markets like those of Trajan, which promote uniformity and repetition through closely grouped tabernae, or small shops as one large system. In contemporary terms, insulae fit organically into a neighborhood like a multi-story apartment building with first floor shops, while Trajan’s Market resembles a shopping mall or “one-stop-shop” environment. (2)

The insula as a building type might as well retain its Ancient Roman name, since the model has undergone very little evolution over two millennia, and has been effectively and sensibly adapted to diverse urban settings across the Western World. What is more, the existence of what could also be called Insula outside of Western zones reaffirm the model’s utility and flexibility, although it will be shown that Ancient Roman Insula provide specific precedent in terms of composition, materials, scale, and rooms.

While it is clear from the study of ruins that Roman Architects favored rational orthogonality, many cities, including Rome, have organic, meandering city plans, which can be attributed to topology and iterative site reuse. In the City of Rome, this geometric irregularity at the level of the urban block resulted in residential building plans of various residual shapes – a result rarely observed (unless intentional) in public spaces and structures. In addition, by serving as a flexible urban poché, most ancient insulae have been replaced by newer, if similar structures [1]. For these two reasons, this genre study will use one representative building; The House of Diana at Ostia, which exemplifies the key characteristics and functionality in a straightforward manor (since the plan is orthogonal), and is widely accepted as the best remaining insula ruin site available for analysis. A detailed examination will aim to characterize the building and site, which will be extrapolated and applied to its genre, where applicable. This examination will focus on three main perspectives:

  1. Patrons;
  2. Site Context, and;
  3. Architectural Characteristics

Finally, examples which relate the building to its contemporary descendants will be offered, illustrating the popularity, longevity, and limitations of the genre.

[1] Many insulae disappeared from existence simply because they were constructed on speculation with non-durable methods and materials, such as timber frame and mud.


The House of Diana is located in the Roman port city of Ostia, located at the mouth of the River Tiber, which feeds the Mediterranean. Ostia, which was a military bastion, or castrum, features a rigid grid plan for streets and property division. The city’s proximity to the Sea and to Rome itself – only about 25 km – allowed for a diverse spectrum of residents, from various socio-economic classes. This diversity contrasts with the City of Tivoli, which is about the same distance from Rome but inland, because Tivoli served as a recreational retreat primarily for the elite and ruling classes, as seen in the case of Hadrian’s Tivoli Villa. Ostia’s residents ranged from the wealthy elite and powerful senators, to seaport workers. At one end of the spectrum, archeological garden house sites (similar to an urban villa) such as the House of the Infant Bacchus, House of the Paintings, and House of Jupiter and Ganymede, are among the most illustrative examples of the ancient villa lifestyle of excess (2). Elaborate atrium houses with painted frescos, mosaics and statuary contribute to Ostia’s reputation as an archeological treasure trove.

Covering more of the spectrum is the case of the House of Diana. Here, artwork and square footage was deployed more sparingly and sensibly, effectively utilizing an almost vernacular quality, though still rich in content. The first floor was rented to commercial tenants, which occupied tabernae along the perimeter walls. These tabernae were slightly elevated from the street, but not set back from the street more than a few feet to allow for a walking path. Tabernae merchants were business tenants, and sold items for daily life, such as food supplies and household goods. Although not clear for a specific insula, it is accepted that the building’s administration was managed by wealthy developers (probably elite patriarchs), who acted as owners and landlords.

Above the commercial story, the building featured four stories of residential housing, where the first residential floor was reserved for the buildings merchants, allowing them to live above their shops (3). The lower floors were considered most desirable, and rented for a higher cost. They were also more lavish, boasting heat and large floor plans (a cistern and auxiliary basins for water and a latrine for sanitation were provided for communal use). The upper stories contained units which were smaller in size, less technologically elaborate, and more affordable. This variation in rent cost alone effectively serves a key principle in modern urbanism today, which is that a diversity of socio-economic backgrounds best provides a higher functioning, and more socially just community.

Site Context

The site context of the House of Diana and countless other insula examples is perhaps the most interesting aspect for examination. The colocation of dense residential quarters with commercial entities provided a springboard for urbanism to spread throughout the territory of the Roman Empire. While this principle trait of the common European, Middle Eastern, or North African city may seem to be the only rational, if not obvious method of community planning, it is worth noting that other urban, sub-urban, rural, agricultural and nomadic models existed before and after the periods of Roman dominance. Immediate proximity to a diverse array of merchants, services, and clientele (residents and consumers) provided a kind of ecosystem of commerce and culture which benefited from an inherent convenience and efficiency. Within the Empire, Romans are thought to be responsible for as many as forty thousand physical insulae. At this scale, it is easy to imagine the street scape, bustling with the energy of commerce, recreation, and daily life.

At the House of Diana, it is worth noting that the block was designed to maximize interaction with the street. This was achieved through the tight proximity to the street and the open format of the tabernae stalls. The stall design featured very wide openings, which welcomed passers-by, while upper windows allowed the admittance of natural light into the space. In a typical insula setting, more of the same would have been echoed across the street, and all around a housing block. Often times, insulae were linked together by structures including atria, private courtyards, alleys, and arcades which allowed a community to grow in an organic and integrated fashion around its physical scaffolding.

House of Diana (shop fronts)

Figure 1. Shop fronts on the first floor (image credit: (4)). In this case, the insula acts as an urban infill building, and maximizes its interaction with passers-by since the building runs right to the street, and contributes to a larger, communal system; the “street wall”. (5)

Human sensibilities for urban optimization and hierarchy were observable in the exterior of the House of Diana. As was typical in multi-story insulae, a balcony ran around the building’s perimeter at a calculated height to allow for a break in typology to occur. Below the balcony, a passer-by would notice qualities befitting a commercial outfit (open stalls, high ceilings, corniced or cavetto eaves), while above the balcony, more reserved details conveyed a private and subdued domesticity. Archeological evidence suggests that this perception was targeted, since in many cases, balconies were not deep enough for functionality, and/or did not coincide with floor levels. However, in a private setting, a functional balcony also offered residents the opportunity to link their private lives with the social life, if they wished, by lingering near or on the overhang, or by conducting household chores, such as laundry, in the airy, cantilevered outdoor room.

Architectural Characteristics

The architect(s) of the House of Diana were apparently well integrated into the ongoing mainstream traditions of Roman building design and construction of the period. The construction of the insula is typically dated at around 150 A.D., based on the presence of advanced concrete. The Insula, which is thought to average about 20 residential units per story, is constructed of Roman brick, which is more slender than most contemporary bricks used in modern masonry. It featured arched and crowned windows, segmental arches, a cavetto balcony and astylar composition (devoid of a canonical order). Above all, the House of Diana seems to be photographed most often for its magnificent relief arches, which incorporate the Roman bricks and slender voussiors. The masonry and concrete work is said to provide character that would have been lost had stucco or other finishes been applied (as was the case in many insula in and around Rome). The rational but imperfect nature of the masonry would have clearly communicated the warmth and scale of the building, while also expressing a welcoming tone to diverse clientele, through its vernacular appearance.

On the interior of the House of Diana, barrel vaults, cross vaults, niches, antechambers, and a latrine have been revealed. Service activities and storage was relegated to dedicated back rooms connected to individual tabernae. Staircases, passageways, a courtyard, and large basins also provided circulation, access and additional amenities. Now badly worn, tiled mosaics, frescos paintings, relief arches, and metal work were found in the site.

Volumetrically, the walls at the ground floor are very massive, indicating a solid tectonic masonry construction, which is consistent with a multistory, astylar building. In fact, insula walls were so stout and reliable, that they were known to be frequently reused in the construction of new structures, such as the light-duty garden house. (2)

House of Diana street elevation

Figure 2. Front elevation sketch of the House of Diana. Featured are large, light-admitting openings at and above the shop entrances, segmental arches, a balcony, and faithfulness to the tripartite system of relative heights (base, column, corona). (6)

House of Diana plan

Figure 3. Ground floor plan of the House of Diana. Key: a – courtyard, b – water cistern, c – public latrine, s – shopping stall. (2) Remaining ruins indicate as many as three stair halls leading residents up to housing levels.

Figure 4 (below). Roman brick and arches permeate contemporary architecture, in forms of symbolism and more literal tectonic expression. Top: A sturdy arch leading to the courtyard in the center of the House of Diana. This composition of structural elements roughly straddles the line between a standard Roman Arch, springing from vertical piers, and a relieving arch, which is embedded within brickwork in order to control the direction and nature of load paths (this hybrid of arch types is noted largely because it is partially filled in). Bottom: Frank Lloyd Wright favored the attenuated Roman brick, since its rectilinear nature emphasizes horizontality if laid flat. Here, Wright designs his Oak Park, IL fireplace in faithful discipleship to the Roman arch builder – a trait that would accompany Wright’s Prairie School style for his entire career. Top and bottom sourced from (6) and (7), respectively.

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Influence and Limitations

As urban settings continued to formalize throughout the territories of Ancient Rome, insluae remained as the most prominent format for urban housing available. In new regions, the apartment block did not resemble the House of Diana, with its masterful relief arches and roman brick, but rather of a variety of local vernacular styles, depending on the culture served. Across Germany, heavy timber structures were erected with plaster walls and wooden carvings of floral Bavarian motifs. In Paris, after the renaissance, multi-use apartment buildings we were rigidly constrained to a common street wall and cornice height – which would eventually provide Paris with its trademark urban boulevards, resembling man-made canyons in which daily commerce would take place. Not all Western cities continued with the apartment block as a mainstream format for urban living. In Protestant countries, such as The Netherlands, Britain, and the American Colonies, there were trends of nuclear families branching out from the extended family, in exchange for a more secluded life. This promoted the need for individual houses for these families to occupy. This would be called the Anglo-American model of urbanism, in contrast with the Continental model (8) traced back to the Roman insula.

Formats of urban apartment buildings remained strikingly similar for centuries, always looking back at the Roman insula, not necessarily as a blueprint or recipe for success, but as a seed of the pedigree set out by these timeless structures. Indeed, the intuitive and optimal habitat for community existence could be adapted to a society’s needs and preferences, and evolution of the format helped to refine life in these environments, allowing for a proper setting for other cultural developments to unfold over generations.

Figure 5 shows contemporary insulae from different corners of civilization. Some have direct lineage back to actual Roman apartment blocks, while others can be traced back to simple rational design. From the top of the Figure, and following around clockwise, settings include Quito, Equador; Hanover, Germany; Tokyo, Japan; Paris, France; and London, England. Each example couples the commercial and the residential in the name of convenience, atmosphere, and practicality. The American apartment blocks, such as the Lower East Side High Rise, the Chicago corner block, and the small town storefront under levels of apartments floors also fall into the same tradition.

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Figure 5. (8)

Apartment formats do not guarantee success for a society, much less a developer. In modern architecture, one trap encountered in the retooling of the model allows pitfalls, where one loses sight of the aspects of the insula which promote a healthy ecosystem of commerce and community interaction. These departures from the aspects of apartments which have led to their success do not represent meanness or disrespect for communities – indeed the appetite for fundamental change in understandable after over two millennia, and society’s turn towards personal ownership of more material goods has promoted a widening of land use – but after only one century, cautionary tales exist which indicate the fragility and balance of the urban apartment block model.

Los Angeles, CA

Figure 6. An Ed Ruscha photograph of a typical apartment in Los Angeles, CA. This building exemplifies mid-century modern design and anticipates post-modernism through an abstract suggestion of segmental arches, which are strikingly similar to those at the House of Diana. Unlike the other examples shown, it lacks a first floor commercial element, which has been replaced by automobile stalls, in accordance with 20th-century preferences, which spread amenities to dedicated zones and buildings, but necessitate the car. (9)

Cabrini-Green, Chicago, IL

Figure 7. Cabrini-Green, Chicago, IL. Modern misinterpretations of the traditional urban apartment block model have neglected the importance of scale and urban context, leading to commercial failure, social injustice, and tragedy (Image credit: (10)). (11)


  1. Economakis, Richard. Summer Drawing Seminar Lecture. University of Notre Dame School of Architecture : s.n., 2014.
  2. Brothers, A. J. Urban Housing. [book auth.] Ian M. Barton (Editor). Roman Domestic Buildings. Exeter, Devon, UK : University of Exeter Press, 1996.
  3. Nash, Ernest. Roman Towns. New York : J. J. Augustin Publisher, 1944.
  4. Stamper, John W. In-class Lecture Notes: “Roman Architecture-e, Housing”. [Also provided title image]
  5. Frederick, Matthew. 101 Things I Learned in Architecture School. Cambridge, Massachusetts : The MIT Press, 2007. ISBN 13 978-0-262-06266-4.
  6. Moore, Timothy J. CC 302: Introduction to Ancient Rome, The Arts of Living. [Online] November 11, 2002.
  7. Frank Lloyd Wright Home and Studio. Wikipedia. [Online] [Cited: November 24, 2014.]
  8. Eric Firley, Caroline Stahl. The Urban Housing Handbook. W. Sussex, UK : John Wiley & Sons, Ltd., 2009. ISBN 978-0-470-51275-3.
  9. Virginia Heckert, Edward Ruscha. Ed Ruscha and Some Los Angeles Apartments. s.l. : J. Paul Getty Museum; 1 edition (April 25, 2013), 2013. ISBN-10 1606061380.
  10. Time Magazine. The End of Cabrini-Green. Time Magazine. [Online] [Cited: November 24, 2014.],29307,2034317_2215123,00.html.
  11. Rybczynski, Witold. City Life. New York : Touchstone, 1996. ISBN 0-648-81302-5.

Author: Nick Rolinski

#Architecture #Urbanism

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