A glory of St. Stephen's Cathedral is its ornately patterned, richly coloured roof, 111 meters (361 ft) long, and covered by 230,000 glazed tiles. Above the choir on the south side of the building the tiles form a mosaic of the double-headed eagle that is symbolic of the empire ruled from Vienna by the Habsburg dynasty. On the north side the coats of arms of the City of Vienna and of the Republic of Austria are depicted. In 1945, fire caused by World War II damage to nearby buildings leapt to the north tower of the cathedral and went on to destroy the wooden framework of the roof. Replicating the original bracing for so large a roof (it rises 38 meters above the floor) would have required an entire square kilometre of forest, so over 600 metric tons of steel bracing were used instead. The roof is so steep that it is sufficiently cleaned by the rain alone and is seldom covered by snow.