Blue Bridge

The Blue Bridge is an arched road bridge across the Moika River in the Admiralteysky District, linking Kazansky and 2nd Admiralteysky Islands and forming part of the ensemble of Saint Isaac's Square. At 97.3 metres wide, it is considered the widest bridge in Saint Petersburg and belongs to the city's group of bridges named after colours — the name has been recorded since 20 April 1738 and comes from the first wooden bridge, whose railings were painted blue. The bridge links Saint Isaac's Square with Antonenko Lane and Voznesensky Prospect; nearby stand the Mariinsky Palace, the monument to Nicholas I and Saint Isaac's Cathedral, while the Red Bridge and Fonarny Bridge lie upstream and downstream.

In 1737 the Dutch master Herman van Boles built a wooden drawbridge on this spot, and by the mid-18th century it had been rebuilt as a three-span bridge on stone piers. In 1818, to a design by Vasily Geste, the bridge became a single-span cast-iron arch made from cast-iron tubbing manufactured at the Olonets Works in Petrozavodsk; the bank abutments were built under the direction of the stonemason Samson Sukhanov. In 1842–1844, in connection with the construction of the Mariinsky Palace and the redevelopment of Saint Isaac's Square, the bridge was widened to a design by the engineers Yegor Adam, Alexander Gotman and Ivan Zavadovsky — new arches of the same construction were added, and the overall width grew from 41 to 97.3 metres.

In the 1920s through-cracks and subsidence were discovered in the old part of the arch, and in 1929–1930, in connection with the laying of a tram line, the span on the downstream side was replaced with a reinforced-concrete arch while the old piers were retained; in 1938 the cobblestone roadway gave way to asphalt. In 1971, on the slope by the bridge, a granite post-gauge with Neptune's trident was installed to a design by the architect Valentin Petrov, marking the levels of the great floods of 1824, 1903, 1924, 1955 and 1967. In 2013–2014 the bridge underwent a large-scale reconstruction: the abutments and cast-iron tubbing were repaired, the waterproofing was replaced, and the railings and lamps were restored based on the surviving torchères by the Baltic Station; traffic reopened on 1 September 2014.