Dominating an intimate cafe-filled square, this millennium-old basilica-church is a fabulous example of Mosan architecture, made 'extra authentic' through 1886–1916 restorations led by Pierre Cuypens (of Rijksmuseum fame). Still a deeply spiritual place, you'll usually come in past pilgrims kneeling at the candle-filled medieval shrine to 'Maria Star of the Sea' and will need to adjust slowly to the brooding darkness of the interior, with its gigantic Romanesque pillars.
The treasury houses a rich cache of jewels and paying the access charge allows you to visit the small north cloister. An audioguide is available (€3) from the shop-stall to the right as you enter the main church.