The Pont Alexandre III (Alexander III Bridge) is Paris's most elegant bridge, ornamented with fine sculpture work, adding its own charm to an already beautiful site.It also owes its fame to the technical prowess that went into its construction. It is made of a single leaf arch that spans the Seine in a great curve, although it is lowered so as not to obstruct the view of the Champs-Elysées or les Invalides. Built in only two years by the engineers Résal and Alby, the first stone was placed by Tsar Nicholas II, although the structure was opened at the 1900 Universal Exhibition. Critics of the time explained the heterogeneous character of the "Exhibition Bridge" by the fact that there were as many artists as there were ornaments. Amongst the decoration are four 17 metre high corner pillars, bearing the four gilded bronze equestrian groups which represent Pegasus held by Fame.