English: Maastricht, the Netherlands. View of the Maastricht underground fortifications or casemates (Kazematten), the elaborate system of casemates, caponiers and the connecting network of subterrainean corridors and mine galeries. They mainly exist on the heigher ground in the west of the city's fortifications (Hoge Fronten) where the use of water as a defense was impeded. The Kazematten are largely intact, even though parts of the above-ground fortifications have been demolished. Access is possible with a guide from the Waldeck Bastion and (for extended tours) from the Linie van Du Moulin. Here a structure meant to reinforce the foundations of a building above ground has pierced a gallery.