The primary tourist attraction of Namur, the Citadel is a fortress at the confluence of the Meuse and Sambre rivers. Its original design dates from Roman times, with foundations laid out in 937. Throughout history it was captured, destroyed and rebuilt several times. It underwent major expansions under Dutch control between 1631 and 1675. Its current topology was designed by Dutch architect Menno van Coehoorn and improved by Vauban after the siege of 1692. A variety of positions were added in the 18th century, but the complex was finally disestablished as a military post in 1891 when it was superseded by a ring of forts around Namur to provide better protection against the improved range of artillery at the time. It saw battle a last time during the German invasion of World War I, after which the new fortifications took over its defensive role. The Citadel is classified as a Walloon Major Heritage site, and together with the citadels of Dinant, Huy and Liège it forms part of the so-called Meuse Citadels. For those unable to climb the hill, a tourist train is available for an additional fee.