During his reign as Emperor of France, a time when architects favored marble and other traditional building materials, Napolean championed the use of iron for monuments and other building projects. Steiner discusses in great detail the Pont des Arts, the roof of the Halle au Ble, and several other cast iron and wrought iron designs chosen or approved by Napoleon. He also explains why, despite the serious interest of French engineers in iron and other new construction materials and Napoleon's close relationship with those engineers, the metal was not utilized on a wide scale.