Caves of Han-sur-Lesse

One of Europe's most impressive cave systems, carved by the Lesse river in the Belgian Ardennes. The tour, about 1.5 hours, starts with a ride on a vintage tram and leads through vast halls of stalactites and stalagmites, ending with a sound and light show and a boat ride out along the underground river.

The ticket can be combined with the wildlife park, where bears, wolves, lynx and bison roam large enclosures, toured by safari truck. The caves stay at about 13°C; bring a jacket.