Several of the most prominent contemporary architects, including Norman Foster, Santiago Calatrava, Zaha Hadid, have turned their attention to designing bridges. One of the most remarkable examples of contemporary architecture and engineering is the Millau Viaduct in southern France, designed by architect Norman Foster and structural engineer Michel Virlogeux. The Millau Viaduct crosses the valley of the River Tarn and is part of the A75-A71 autoroute axis from Paris to Béziers and Montpellier. It was formally inaugurated on 14 December 2004. It is the tallest bridge in the world with one mast's summit at above the base of the structure.