The structure of the existing roof consists of a fixed part and a mobile section in which the structural resistance is conferred to a system of cables which is anchored in a perimeter beam which acts as a compression ring that rests upon a system of column supports.

The perimeter beam is 800x500 and has an 82.0m diameter. The 60mm interior cables form two 36.0m diameter rings which are linked via a system of 16 masts which act as the uprights in the system.

The substitution of the fixed membrane commenced with a staggered disassembly which permitted the maintenance of the geometry of the system. The membrane is composed of four sections which have to be disassembled symmetrically. Provisional cables are set up in a diagonal cross-form which allows the disassembly, in such a way, that the original shape is not lost.