The Colosseum’s new arena floor is a web of mechanically controlled wooden slats

Following the Italian Ministry of Culture’s announcement inviting bids for restoring the floor of the Colosseum’s arena earlier in January this year, a mammoth task in scope and cultural value by all means, several internationally renowned practices submitted proposals that could land a precise balance between the immense value of the monument, and the state-of-the-art features that the intervention would have to embody in order to keep the floor retractable, and the entirety of the solution, reversible. Last month saw the winning proposal and the announcement of the award of works to a multidisciplinary team comprising Milan Ingegneria, architect Fabio Fumagalli, Labics, Consilium Servizi di Ingegneria, and Croma who propose an automated, radical, and elegant new solution for restoring the Colosseum to its former glory in wood.

Before the pandemic, the ancient Roman monument from the Flavian period attracted close to 20,000 people a day, and the Italian Government, the Ministry of Culture, and the Ministry for Cultural Heritage and Activities for the Colosseum Archaeological Park expect those numbers to be fast incoming in a post-pandemic scenario as well, as euphemistic as that may sound. By 2023, visitors would thus be able to walk at the same level as the ones on which gladiators fought, bringing the Roman amphitheatre much of its infamy and fame, and experience the amphitheatres seating the fickle Roman mobs from a “centred” perspective, from the middle of the arena.

According to the architects and structural engineers on the project, their proposal and vision for the new floor has the protection of the existing archaeological structure as the leading principle behind it, applied both in terms of structure and appearance. The wooden assembly will encompass the entire span of the arena’s floor and can be configured to open partially, in segments, and even completely, closely integrated with prevailing environmental conditions to ensure additional conservation of the complex structures beneath it. In order to provide access to the service corridors and to the Porta Triumphalis and Porta Libitinaria, while staying true to the experience and ensuring minimal alteration to the existing structures, the new floor has been designed at the same level as the original centuries ago, in strict accordance with the brief laid out by the ministry.

Supported on existing masonry and standing atop the original foundations using a particularly thin structural section, the new floor will be built with extremely light albeit high performance materials. The support system for the floor would thus be constituted of multiple layers that will chemically and physically insulate the underground masonry structures, also making them resistant to horizontal seismic stress from visitors walking on the arena floor. The individual composite section is designed in stainless steel, and will enable not only load bearing, but also the installation of bollards to protect the retractable floor, illumination for the underground areas, apparatus for the removal of bio-organisms, and rainwater conservation and collection intended to serve public restrooms. The entire assembly will then be capped off with rotatable and movable panels of a carbon fibre and Termanto composite.

The final facia of all the supporting structures will be covered with Accoya wood, produced using a process that modifies the structure of the timber, allowing it to be sourced from local, sustainable plantations instead of native forests, while also lending the entire assembly resistance against bacteria, insects, rain, and deterioration caused by other adverse weather conditions. The wooden sheath has been chosen to be stylistically and tonally similar to the underlying archaeological remains, even when the floor is closed. By selectively opening and moving these slats, innumerable such configurations can help put on quite a show for visitors and tourists, revealing the detailed underground structure: an intricate network of tunnels, chambers, and lifts, in quite a grandiose and theatrical manner. A glimpse at the underground from the level of the floor is intended to offer visitors an insight into its interaction with what used to happen on the floors of the arena. Not only does such modularity allow for effective segregation and compartmentalisation of the Colosseum’s daily activities, including maintenance, conservation, and visitor experience, it also allows for differential views of the space each time and an amplification of the effect of natural light on these spaces.

An essential, possibly overlooked aspect of the original design that may be enhanced by this technological intervention, is that of its supposed ability to influence the microclimate. By using a carefully maintained ratio of closed surface to open, their duration, exposure to sun, humidity, and wind velocity, the automated system of slats across the floor helps personnel maintain optimum conditions for preservation of the ground underneath, almost always. If necessary, it will be possible to carry out air renewal of the whole area below the new floor in just 30 minutes by activating mechanically controlled ventilation units along the perimeter of the underground area, symmetrically located along the east west axis. By being entirely reversible, and building “upon” as opposed to “in place of”, this intervention proves to be completely respectful of its past while looking to a coexistent future.

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Project Details

Name: The Colosseum’s new Arena Floor/ Nuovo piano arena del Colosseo
Location: The Colosseum, Rome
Year: 2021-2023
Project leader/ Structural Design and Safety: Milan Ingegneria
Head of Integrated Specialist Services and Architectural Design: Architetto Fabio Fumagalli
Architectural Design: Labics
Systems design: Consilium Servizi di Ingegneria
Restoration: Croma

Read about the announcement inviting designs and bids for the restoration of the Colosseum’s hypogeum by the Italian Ministry of Culture, here.