Barcelona has always been known for having a special sensitivity and respect towards its past, but at the same time for its forceful commitment to the future and the avant-garde. Las Arenas is a clear example of this, and it reveals the confluence of both concepts: historicist architectural respect and technological commitment. The old bullring, in disuse since 1989, had become a symbol after more than a century; not so much for its architectural value as for being part of the city’s landscape. Hence, the architectural project was oriented towards its maintenance, like a second exterior skin of the new building. However, such preservation entailed great technical complexity: firstly, due to its evident physical deterioration; and secondly, due to its strange level, which is 4m high above the perimeter streets. The technical effort was aimed at presenting the cylindrical, forceful and atypical shape. The solution to create a new façade under the existing façade consisted of creating a large perimeter pathway of exposed reinforced concrete to which the upper weight is transmitted. Also temporarily, the entire façade rested on a circular metal crown. Once restored, it would become a kind of double skin exempt from direct contact with the new building. A circular metal walkway would fulfill a triple function: cable stay, fire evacuation corridor and services, facilities and supply of goods. The building has a huge central void which works as a reception hall for all the activities of the complex - commercial, recreational and leisure - from which to observe the life and effervescence of movement of the complex. The roof of the building was another of the great challenges of technical and structural resolution, since it was separated from the rest of the building to emphasise its sense of buoyancy. We stand before one of the largest domes in Europe, with a multitude of uses and possibilities, as well as a perimeter promenade from which to enjoy the magnificent view of Barcelona, at a height of 27m and with a length of more than 300 linear metres. A special vaulted space in the context of a city that has always lacked them, and that highlights the uniqueness of the project - always in line with the identity of Barcelona. It is also a project developed in partnership with Richard Rogers, contributing and complementing points of view to go beyond the initially set objectives.