Colosseum: Enhancement and Revitalization of the Southern Ambulatory Areas
The project to enhance the Colosseum’s southern ambulatory, developed by Stefano Boeri Interiors, founded by Stefano Boeri in collaboration with architect Giorgio Donà, represents a spatial recomposition intervention aimed at restoring the southern perimeter of the Flavian Amphitheatre and giving renewed legibility to its southern ambulatory areas. Following a campaign of archaeological investigations, the design included the restoration of the original levels and crepidine, as well as the repaving of the missing sections of the southern ambulatory, offering visitors a clearer understanding of the monument’s original layout.
In light of the excavation activities conducted by the Parco Archeologico del Colosseo and the project requirements that emerged, the intervention—focusing on the Colosseum’s southern façade, between arches 60–76 (Valadier side) and 1–18 (Stern side)—primarily involves the restoration of the ancient crepidine, the double perimeter step that defines the base of the monument and serves as an architectural boundary between the Colosseum and the piazza (still visible in its original form on the northern side). To achieve this, a controlled lowering of the piazza levels was carried out, reaching approximately –1 m near the southern arch, allowing for the emergence of two uniform risers of 19 cm and a tread of 38 cm.
Based on the archaeological investigations conducted by the Parco Archeologico del Colosseo and the geometric study carried out by Stefano Boeri Interiors, and thanks to the contributions of prior research* (Source: Camillo Trevisan, Sullo schema geometrico costruttivo degli anfiteatri romani: gli esempi del Colosseo e dell'Arena di Verona; Jean-Claude Golvin, L'Amphithéâtre romain: essai sur la théorisation de sa forme et de ses fonctions, Boccard, Paris 1988, pp. 284–288), it has been possible to confirm that the excavation area aligns with the geometric study of the monument. The superimposition of the excavation perimeter onto the geometric layout allowed for a more precise definition of the restoration of the crepidine’s perimeter.
The work of controlling and restoring the monument’s original levels not only reinstated the legibility of the Flavian Amphitheatre’s footprint and its geometric base, but also offered the opportunity to reconsider the stormwater drainage system. The altimetric redefinition of the piazza enabled a thorough analysis and optimization of rainwater runoff, calibrating slopes and transitions in coherence with the monument’s original layout. The result is a public space that is both hydraulically organized and more accessible for visitors, where water management becomes an integral part of the paving design.
The paving system of the Colosseum’s southern ambulatory is structured through a design that interprets the Flavian Amphitheatre’s generating geometry in a contemporary key. The arrangement of the slabs makes explicit the radial pattern governing the entire monument. Covering an area of approximately 3,130 m², the surface is organized into a grid with alternating bands: regular bays are interspersed with compensation strips, a technical solution that absorbs geometric variations imposed by the curvature of the crepidine.
The slabs, trapezoidal in shape with variable geometry, are aligned along the optical axes of the arches, directing the visitor’s gaze toward the monument. The installation of travertine slabs restores the ambulatory spaces as unified and walkable areas, where the ground pattern becomes a tool for a critical reinterpretation of the original spatial configuration. In contrast to the urban paving in cobblestones, the ambulatory area is treated with Classic Travertine from the Cava del Barco, cut along the bedding plane to ensure material and chromatic continuity with the original surfaces.
The project includes marking the disappeared structures along the monument’s southern façade with two types of “imprints” integrated into the pavement: 44 extruded elements, 40 cm high, that allow the reading of the original plan while functioning as seating, and 8 flush elements at ramps and circulation nodes, identifiable through a textured bush-hammered finish that indicates pathways without obstructing visitor flow.
At the same time, the design ensures full accessibility through the insertion of access ramps located at the ends of the route and at what originally constituted the monument’s southern annex. This system allows visitors to overcome the level differences created by the restoration of the historical elevation, making the area continuously and inclusively navigable while integrating the access devices into the new spatial configuration.
The intervention was designed according to principles of reversibility and accessibility. The solutions adopted preserve the integrity of the site while allowing the structures to be removed or modified without compromising the existing elements.
Between arches 65 and 71, the pavement is interrupted to create an archaeological window descending to an elevation of +21.32 m a.s.l., allowing a clear view of the foundations and historical stratifications. Within the exposed archaeological sector, the excavation perimeter is defined by tuff blocks, finished with metal profiles and glass railings, ensuring that the intervention remains fully reversible.
In ancient times, each arch—except those located along the major and minor axes—was marked with a number engraved on the top of the arch, just below the first cornice of the façade, to facilitate identification of the entrances. The collapse of the southern ambulatory led to the permanent loss of the original numbering in that sector. To restore the historical legibility of the monument, the project foresees the reintroduction of progressive numbers on the ground corresponding to each arch.
The reconstruction is based on an analysis of the northern façade, where the original elements are still preserved; from these, the height of the characters, approximately 40 cm, has been determined. The numbering will be engraved on dedicated travertine slabs, measuring 120 × 60 cm, aligned with the entrances, thereby ensuring the continuity of the original orientation system.
