Heks - orange - 5,7 km

Beneath the fertile loam lies a permeable layer of limestone. The Romans already used this limestone (known locally as marl) in their constructions. The Heerse limestone was also very useful in the construction of many Haspengouw churches, including the basilica of Tongeren. Between 1930 and 1960, millions of mushrooms were cultivated in these former marl quarries. Today, these caves (also called marl pits) are one of the main wintering sites for bats in Western Europe.