The Trasshöhle in the Brohltal valley is an impressive artificial cave, created by the extraction of trass , a volcanic binding agent. These "caves" near Burgbrohl in the Eifel region were formed after the devastating eruption of the Laacher See volcano approximately 13,000 years ago. During this eruption, a swirling, red-hot stream of volcanic ash and debris ("trass") filled the Brohltal valley to a height of up to 60 meters.
The Romans began mining trass in the Brohltal Valley early on, but from the 17th century onward, the Netherlands became the largest buyer, particularly for waterworks: trass cement can harden underwater and was ideal for building dikes and locks, for example. The rock was quarried and stored in the "Trasshöhlen" (trass caves). Later, these caves were used by the local population for storage and livestock stables, but now they are unique geological and cultural attractions that you can explore on foot.
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