Dome

Cross section view of the interior central vaulted space and side booths; Original architect's drawing, part of the Paris on Stage: 1889-1914 exhibition held June 19, 2013 to February 23, 2014. The Galerie des machines (officially Palais des machines) was a pavilion built for the Exposition Universelle (1889) in Paris. It was located in the Grenelle district. The huge (area of 115 by 420 meters) pavilion was made of iron, steel and glass, and was by far the largest vaulted building to have yet been built. It had no internal supports but used 20 cast iron trusses. It was reused for the 1900 exposition, and later used as a velodrome, agricultural exhibition hall and for other purposes. It was demolished in 1910 to open up the view along the Champ de Mars. Source: Wikipedia; http://en.wikipedia.org/wiki/Main_Page (accessed 6/25/2015)