At Christmastime, the entire city of Valkenburg seems to sparkle with festive light. The annual underground Christmas market is a hallmark of the city, lasting from mid-November through December 23. It’s held in the Velvet Caves, a maze of 12th-century passageways that lies beneath the remains of Valkenburg’s hilltop castle. The caves and castle draw visitors year-round. Valkenburg is a biking city. It's a great base for cycling tours and is a two-time stage finish site for the Tour de France.