Under avenue Foch in Paris, the eponymous parking, built in 1967, still has 2,030 spaces and is therefore not yet an automotive wasteland. However, since March 2025, Indigo and Corsalis have been transforming part of it into an urban logistics space of 12,000 m². In the long term, heavy trucks, electric vans and cargo bikes will cross there to ensure the last mile deliveries; the whole area must also accommodate tourist buses, a Cyclopark with 200 spaces and more than 200 charging stations. The parking remains a parking but no longer only. At Bercy, Indigo and Corsalis have gone even more radical: about 2,000 m² of a parking have been completely transformed into an urban logistics space. At La Défense (Hauts-de-Seine), ENIA architects had already found enough qualities in the underground parking spaces to insert part of Table Square. These are holes in the city but precious holes. They have ramps, accesses, networks, sometimes large surfaces and, a non-negligible advantage in Paris, they exist. "City center parking lots are today less used: what do we do with this heritage?" asks Loïc Brenterc’h. The architect associated with Nelly Bussac within ABA Workshop has an answer: especially not to decide too quickly. Storage for merchants, self-storage for residents, logistics, bikes, electric charging, car rental, data centers... Loïc lists the possible uses but the list ultimately matters less than its principle: preserving plasticity. "Where will we be in ten years?" Nobody knows. It is annoying for an architect. Even more so for his client. Because it is relatively easy to tell what an existing parking could become, the exercise becomes more interesting when it is necessary today to build a new one. The need is there, we have seen it: hospitals, stations, airports, peripheries, large facilities. But how to invest several million euros in a building that it is admitted from the first stroke of the pencil that its function may disappear? One answer is to make the parking convertible. Higher under the ceiling, flatter, stronger, more generous in its frames, it may tomorrow welcome offices, housing or other programs. William F. Kavanagh, an American architect who claims to have more than 500 parking lots to his credit, has nevertheless taken on the task. In In Context, the magazine of the AIA Philadelphia, he published in May 2025 an article with a sufficiently explicit title: Parking Garages, A Contrarian Perspective. His reasoning consists of a question: why build today a bad parking in the hope of making it tomorrow an average building? To allow a transformation into offices or housing, he explains, it is necessary to increase the floor heights, modify the structural spans, accept more pillars, provide higher loads, different placements of cores and circulations, possibly light wells and floors that will have to be brought up to standard. All of this costs money. In his case study in Philadelphia, two parking lots with about 600 spaces, the structure designed for a future transformation costs 54% more than the one optimized for parking alone. This obviously does not demonstrate that reversibility is a bad idea. Kavanagh himself admits that reusing a structure avoids eventually waste and new materials. However, his calculation has the merit of spoiling a bit the party: flexibility is not free and planning for a future that may never come can cost a lot today. Loïc Brenterc’h proposes another way to approach the problem: if the building cannot become something else, perhaps it can be useful elsewhere. In Bissen, Luxembourg, ABA Workshop participated with Thomas Rau and several partners in the design of Loop Park, a parking for about 500 places for the Innovation Campus. Here, the demand was originally strange: to build a structure that can accommodate cars or offices and whose elements can be disassembled and reconverted according to future needs. Modular metal truss, components designed according to the principles of circular economy: ABA Workshop describes it as "completely modular, evolutionary and recyclable." The announced amount is 7.264 M€ HT for 15,000 m² of operational surface. "Assembled, disassembled and reassembled," he says. At worst, he explains, the foundations remain. He mentions that the cost of moving and reassembling reduces the price of the work by 50%, figures difficult to confirm. On the other hand, the principle of the project is perfectly documented: Loop Park is designed so that its components can be disassembled and reconverted.