The Millau Viaduct was built in only three years, thanks to a meticulous preparation that lasted 14 years. Several layouts and sites imagined in order to cross the Tarn valley were discussed. In 1996, the project for a multi-stayed bridge was chosen instead of a bridge with constant or variable thickness, an underbanded viaduct, or a single central arch. Michel Virlogeux, chief engineer, and Lord Norman Foster, architect, collaborated with the Eiffage group for the construction that started in 2001. Inaugurated in December 2004, the Millau Viaduct is considered a major architectural work of the 21st century.