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Roman Insula (Rome)

Description

Piazza d'Aracoeli

Tel. 06-0608
Bus: 40, 62, 63, 64, 110, 170.
Trolleybus: 8
Open by appointment only: call first.

The Insula dell'Ara Coeli, often referred to as the Ara Coeli Insula or Capitoline Insula, stands as one of the most significant surviving examples of ancient Roman urban housing. Located at the foot of the Capitoline Hill in Rome's historic center, specifically at Piazza d'Aracoeli (coordinates approximately 41°53′38.64″N 12°28′56.33″E), this multi-story apartment block was constructed in the early 2nd century AD during the height of the Roman Empire. It exemplifies the insula (Latin for "island"), a type of tenement building that dominated Rome's residential landscape, housing the city's dense population of artisans, merchants, laborers, and middle-class families amid rapid urbanization. Unlike the luxurious domus for the elite, insulae like this one addressed the housing crisis caused by Rome's population exceeding one million, with limited land forcing vertical construction.
This structure, nestled adjacent to the monumental staircase leading to the Basilica of Santa Maria in Aracoeli, offers a tangible glimpse into everyday Roman life. Today, it is partially visible from the street and accessible by reservation for groups, highlighting its role as both an archaeological site and a testament to Rome's layered history.

History

The insula's origins trace to the early 2nd century AD, aligning with the reign of Emperor Trajan (98–117 CE), a period of architectural innovation and urban expansion in Rome. This era saw the construction of nearby landmarks like Trajan's Market, reflecting the empire's prosperity and the need for efficient housing in the densely packed Region VIII (Forum Romanum). Brick stamps and the use of opus latericium (brick-faced concrete) confirm this dating, a common technique in imperial building projects for durability and speed.
The building underwent multiple phases of modification, including repairs and expansions into late antiquity, likely due to fires, earthquakes, or urban wear—common hazards in ancient Rome. Its location on the Capitoline's slopes bridged sacred and civic spaces, transforming peripheral areas into vertical residential zones to support the Forum's economic activities. By the medieval period, the insula was partially buried and repurposed; a Romanesque bell tower and a 14th-century frescoed arcosolium from the Church of San Biagio de’ Mercato (later Santa Rita da Cascia in the 17th century, designed by Carlo Fontana) were integrated into or built atop it. This layering demonstrates Rome's "architectural recycling," where ancient structures supported later Christian buildings.
In the broader context of Roman insulae, this example highlights social stratification: ground-floor commercial spaces catered to trade, while upper apartments housed diverse residents, reflecting the empire's multicultural urban fabric.

Discovery and Excavation
The insula remained hidden for centuries until the 20th century. It was rediscovered between 1929 and 1933 during Benito Mussolini's ambitious urban renewal program, which aimed to glorify Rome's imperial past by clearing medieval and Renaissance overlays on the Capitoline Hill. Demolition of the Baroque Church of Santa Rita da Cascia (relocated near the Theater of Marcellus) and surrounding structures exposed an entire Roman neighborhood, including the insula, the Casa Cristiana, Taberna delle Tre Pile, Caseggiato dei Molini, and a bathhouse (balneum).
Excavations revealed the original street level, significantly lower than today's Piazza d'Aracoeli, showcasing how sediment and construction raised Rome's ground over millennia. The process uncovered not just Roman elements but also medieval artifacts, underscoring the site's continuous occupation.

Archaeological Research and Studies
Early documentation came from A. M. Colini (1930) and I. Gismondi, with J. E. Packer providing a detailed description in 1968/69. The most comprehensive analysis was by classical archaeologist Sascha Priester, who examined the site from 1997 to 2002 as part of a broader study on Roman insulae. His 2002 publication, Ad summas tegulas, integrated archaeological, epigraphic, and literary sources, refining reconstructions and refuting earlier assumptions of a four-wing layout. Modern efforts include 3D laser scans and animations (e.g., a 2014 photographic model), aiding visualization.
Nearby, an aristocratic domus on the Arx (northern Capitoline summit) was excavated in the 1980s, dating from the 1st century BC with Flavian and 3rd-century AD renovations, but it is distinct from the insula.

Significance and Legacy
The Insula dell'Ara Coeli is invaluable for understanding Roman social dynamics, economy, and architecture. It reveals class divisions—luxurious lower apartments versus precarious upper ones—and the integration of commerce with residence. As noted by scholar Andrew Wallace-Hadrill, its fourth-floor suites resemble modern 40-square-meter apartments, bridging ancient and contemporary urban living.
Its preservation amid Rome's transformations—from imperial hub to medieval religious site—underscores the city's resilience. Today, it influences studies on ancient urbanism and inspires modern high-density housing designs. Visitors can view it externally or book tours, preserving its educational role.

Description

Overall Layout and Reconstruction
Early scholars like A. M. Colini and J. E. Packer envisioned the insula as a four-wing complex encircling an inner courtyard, similar to other Roman insulae. However, Sascha Priester's detailed analysis (1997–2002) revised this model, identifying it as a three-part structure: a west building (largely obscured by modern Via del Teatro di Marcello, except for its massive brick facade), a north building with a filled-in staircase, and the prominent east building (the visible "Insula dell'Ara Coeli"). Rather than a closed courtyard, Priester proposed a vaulted alley (via tecta or vicus)—approximately 3.8 meters wide including porticos—running between the west and east wings. This alley entered from the west, turned south at the north building, and possibly branched eastward, providing internal circulation and shelter. Evidence includes portico pillars, arch remnants, and brick pillars supporting the vaulting. The alley was paved in a secondary phase and abandoned in late antiquity, highlighting the building's evolution. The east and west buildings differed in height, with the overall complex designed for mixed-use efficiency in a sloping urban terrain.

Materials and Construction Techniques
The insula exemplifies Imperial Roman construction, primarily using opus latericium caementicium—brick-faced concrete—for durability and fire resistance. Brick was extensively employed in facades, pillars, and walls, with the west building's facade standing as a massive, imposing element. Upper floors likely incorporated lighter wooden framing to reduce weight, a common cost-saving measure that contributed to the era's frequent structural issues. The building's foundations adapted to the Capitoline's slope, with vaulted arches and porticos providing stability and aesthetic uniformity. Ceiling heights diminished progressively upward—from spacious lower levels to cramped attics—optimizing space while adhering to height regulations (though often exceeded in practice). Medieval integrations, such as the stone bell tower and frescoed arcosolium, were built directly onto the Roman fabric, demonstrating architectural recycling.

Floor-by-Floor Description
The insula's vertical hierarchy mirrored social status, with better accommodations lower down.
Ground Floor: Situated below modern street level, this featured a row of tabernae (shops and workshops) opening onto the street via large portico arches, some spanning up to 400 square meters. These commercial spaces supported artisans and merchants, with access to upper living quarters via ladders or internal stairs.
Mezzanine (First Upper Level): A low-ceilinged intermediate floor above the tabernae, likely used by shop owners for living or storage, providing a buffer between commerce and residences.
Second Floor (Piano Nobile): Corresponding to the current street level, this "noble floor" housed spacious, well-lit apartments for affluent tenants, featuring multiple rooms and access to natural light via windows and the alley.
Third Floor: Large apartments with generous layouts, suitable for middle-class families, emphasizing comfort with broader room spans.
Fourth Floor and Above: Narrower corridors led to three-room suites, each including a main living area illuminated by two windows, plus rear rooms for sleeping and utilities—resembling modern compact apartments. Upper levels were smaller and more cramped, for lower-income residents, with at least five stories originally (four to five preserved today).

Additional Architectural Features
Key elements include the porticoed facade for public engagement, brick pillars supporting the vaulted alley, and arched openings for light and ventilation. The structure lacked advanced amenities like running water on upper floors, relying on public fountains, and sanitation was basic with shared latrines. Medieval overlays, such as the 12th-century Romanesque bell tower and 14th-century fresco depicting saints, were integrated into the facade, illustrating Rome's continuous urban evolution.

Modern Studies and Conservation
In 2014, a collaborative laser scanning project by Archaeovision and the Sovraintendenza Capitolina ai Beni Culturali captured 205 scans over six days, creating a detailed virtual model. This revealed intricate room interrelations, hard-to-access features like upper-level alignments, and the building's phased construction, aiding future excavations and conservation. The data supports plans to transform the site into a public museum, though it remains exposed to the elements and largely inaccessible.

Site reconstruction

According to the reconstructions of the archaeologists Antonio Maria Colini and James E. Packer, the remains belong to a large multi-storey complex with four wings grouped around an internal courtyard.

The German archaeologist Sascha Priester, based on the archaeological remains and the remaining documentation, proposed a new reconstruction of the area: There was a "West Building", which today, except for its massive brick facade still visible, it is almost completely under the modern Via del Teatro di Marcello. The surface of this ground floor with its row of shops (tabernae) was up to 400 m². A "North Building", which could have access stairs to the inside, would have been reinterred immediately after the discovery. A "south wing" which until now had only been assumed hypothetically, has never been. Instead the "East Building" - now known as Insula dell'Aracoeli - is the most visible part of this building situation. Between the "West Building" and the Insula of the Aracoeli S. Priester has reconstructed an alley, crossed by arches; the porticoed pillars of the "East Building" and the traces of arches and the corresponding brick pillars of the opposite "West Building" are proof of this. Due to the subsequent extension of the portico of the Insula dell'Aracoeli this street as a via tecta was reduced in width to about 3.8 meters. The alley was quietly paved in a secondary phase and was eventually abandoned as a roadway at the latest in Late Antiquity.