This is the Alésia Museum designed by Bernard Tschumi Architects. The museum commemorates a battle that occurred between Julius Cesar and the Gauls some two thousand years ago where the museum now stands. Although the scheme for the museum includes two buildings, these images are of the Interpretive Center. According to the architects:
The interpretative center is built of wood, much as the Roman fortifications would have been at the time of the siege. The roof of the building is a garden planted with trees and grass, camouflaging the presence of the building when seen from the town above. Visitors may look onto reconstructions of the Roman battlements from the roof garden, or stroll down a path to experience the reconstitutions first-hand.