The Covered Bridges (Ponts Couverts) extend from the Petite France district. They have retained their name despite the disappearance of their roofs in the 18th century. They are dominated by three 13th-century towers, remnants of the old ramparts, guarantors of the independence of the Strasbourg Republic. Immediately after Strasbourg was annexed by France in 1681, a new ring of fortifications was built by Vauban.They have retained their name despite the disappearance of their roofs in the 18th century. They are dominated by three 13th-century towers, remnants of the old ramparts, guarantors of the independence of the Strasbourg Republic. Immediately after Strasbourg was annexed by France in 1681, a new ring of fortifications was built by Vauban.