Blue Bridge, St. Petersburg

The widest of all the 342 bridges in St. Petersburg, the Blue Bridge (Russian: Siniy Most) can easily pass unnoticed whilst carrying the entire St. Isaac's Square on its back across the Moika River in front of the Mariinsky Palace. Located between Saint Issac’s Cathedral and the City Hall, the bridge has its ends fixed on the massive stone abutments on the river shores.

The first cast-iron bridge on this site was built in 1818, designed by the Scottish-born Russian architect William Heste (Hastie) in 1805. The original overpass was a single span and measured 41 meters across. In 1842–1844 it was renovated and doubled in width towards the current 97.3 meters (319 feet). Contrary to the erroneous claims that the Blue Bridge is the widest bridge in the world, it is not.

The name of the viaduct derives from the elegant, cast-iron railings painted a distinctive shade of sky blue, which was part of a 19th-century tradition of color-coding the bridges crossing the Moika. The Blue Bridge is one of the four color-coded bridges still in existence; the others being the Red, Green, and the Yellow. Three of them have kept the original names, while the Yellow one has been renamed Pevchesky (Singer's) Bridge.

Prior to the abolition of serfdom in 1861, the Blue Bridge often served as the marketplace for serfs. Today it functions as a parking lot for the municipal parliament.