The Simone Tower, also called the Devil’s Tower and located close to the collegiate church Sainte-Gertrude of Nivelles, was for many years the premises of the League of Crossbowmen (Serment des arbalétriers), one of the civilian bodies charged with defending the ramparts of the city. Renovated in 2006, this tower is now the last testimony to the medieval walls which were constructed in the 12th century. There were no fewer than eleven towers and seven portcullis gates. The rampart was composed of a mighty fortification 2.50 m thick, surrounded by partially flooded moats outside, and reinforced with 8 m-wide embankments inside. In the tower, the guardroom, vaulted and pierced by arrow-loops, now houses a 3 dimensional map of the city of Nivelles as it looked around 1600, defended by the rampart and its moats. The tower is now accessible as part of a guided visit of the city of Nivelles.