Le Corbusier used raw concrete to construct the convent, which is placed on the side of a hill. The three blocks of dormitories U, closed by the chapel, with a courtyard in the center. The Convent has a flat roof, and is placed on sculpted concrete pillars. Each of the residential cells has small loggia with a concrete sunscreen looking out at the countryside. The centerpiece of the convent is the chapel, a plain box of concrete, which he called his "Box of miracles." Unlike the highly finished façade of the Unité d'Habitation, the façade of the chapel is raw, unfinished concrete. He described the building in a letter to Albert Camus in 1957: "I'm taken with the idea of a "box of miracles"...as the name indicates, it is a rectangual box made of concrete. It doesn't have any of the traditional theatrical tricks, but the possibility, as its name suggests, to make miracles." The interior of the chapel is extremely simple, only benches in a plain, unfinished concrete box, with light coming through a single square in the roof and six small band on the sides. The Crypt beneath has intense blue, red and yellow walls, and illumination by sunlight channeled from above. The monastery has other unusual features, including floor to ceiling panels of glass in the meeting rooms, window panels that fragmented the view into pieces, and a system of concrete and metal tubes like gun barrels which aimed sunlight through colored prisms and projected it onto the walls of sacristy and to the secondary altars of the crypt on the level below. These were whimsically termed the ""machine guns" of the sacristy and the "light cannons" of the crypt.