Built for the 1900 Paris World Fair, the Grand Palais des Beaux-Arts is a masterpiece of stone, glass, and steel. The 240-metre-long building is topped by a glass roof that takes up a quarter of its surface. The dome is 45 metres high and rests on four cut-out metal pillars. The metal structure of the nave is composed of large steel beams assembled and riveted together, leaving a large space on the ground without intermediate posts. The glass roof of the Grand Palais, which was studied at length by the architects Deglane, Louvet and Girault, provides a soft, filtered natural light that is well suited to the works of art.