This building, which dominates the Observatory and the forest of Meudon, is designed for the study of the Sun. On its upper platform, under a mobile dome, is a heliostat, a set of two mirrors that sends the light of the Sun vertically to an analyzing instrument, a very efficient spectrograph. The solar specialists at the Observatory can also use the international observatory THEMIS, on the island of Tenerife, in the Canary Islands, and also observe the radio emissions of the Sun from the Nançay radio-astronomical observatory.
