Fluweelengrot (Velvet Cave)

Candle-lit passages under Valkenburg castle, dug by marl miners and used by castle defenders for centuries.

The Velvet Cave grew alongside the castle above it: secret escape stairs, chapel niches and charcoal drawings line the corridors, and guides fill an hour with siege stories. In December the cave hosts Valkenburg's famous underground Christmas market. Tours run year-round — it's always a cool 12°C, so bring a layer. Combine with the castle ruins ticket for the full story.

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