The Collegiate Church of Sainte-Waudru is the great Gothic church that has dominated Mons's hilltop since the 15th century. It was built over two hundred years to house the relics of Saint Waudru, the 7th-century abbess who founded the religious community from which the city grew. The building is unfinished — a planned tower was never completed — but what stands is impressively large and beautifully proportioned.
Inside, the church is full of art: Renaissance alabaster altarpieces, carved stalls, and a remarkable treasury. The star exhibit is the Car d'Or, the golden ceremonial carriage in which Saint Waudru's relics are paraded through the city each year on Trinity Sunday for the Ducasse de Mons festival. The church is open daily and free to enter; the treasury charges a small admission.