Paris is a city of contrasts: light and dark, old and new, past and present. Erased from the memories of most Parisians, however, are two buildings: the Palais du Trocadéro and the Palais Bardo. These ephemeral constructions of grandeur were richly imagined for the Expositions Universelle, World’s Fairs, that were held in Paris every eleven years beginning in 1855 and ending in 1937.