Block 1 is the first building in the ZAC (mixed development zone) TGV Belfort Montbéliard. It uses a principle of “multi-programme” blocks, combining different architectural programmes within a unified and coherent group of volumes articulated around two patios (a hotel and offices). Its massing is based on the three “horizon lines” given in the specifications for the mixed development zone: a pedestal with a single storey (+1), serving to integrate the addresses and accesses; the two emergences of the hotel and offices are +3; and lastly what is called the “Tower”, which is +5 (on a 33 m x 33 m plan with central core).