Ofenkaulen, Underground quarry system in Königswinter, Germany.
The Ofenkaulberg mountain contains an extensive network of mining tunnels created through centuries of trachyte tuff extraction for oven construction.
During World War II, the tunnels housed a weapons factory where 400 forced laborers from Russia and Poland manufactured injection pumps for fighter aircraft.
The quarry gained recognition in the 19th century for producing high-quality stones known as 'Königswinter Ovens', used throughout the region for baking.
The tunnels remain sealed with concrete since the 1980s, with small entry slots maintained exclusively for bat populations that winter inside.
Modern technology enabled the creation of a detailed 3D model of the tunnel system, allowing virtual exploration of this otherwise inaccessible site.
Location: Königswinter
GPS coordinates: 50.67850,7.22016
Latest update: May 12, 2025 09:27
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