Prüm explosion

On 15 July 1949 an ammunition depot exploded on the hill of Kalvarienberg in the Eifel mountains, in western Germany near the border with Luxembourg. The cause of the explosion, in which the town of Prüm was heavily damaged and 12 people killed, was never discovered. The crater, which is still visible today, is one of the largest man-made explosion craters in existence. A cross on the Kalvarienberg commemorates the victims of the disaster.

When the Siegfried Line was built in 1939, a standby bunker was constructed for the Wehrmacht inside the Kalvarienberg. The underground bunker was located 20 to 30 metres below the top of the hill and consisted of a 100-metre-long and a 60-metre-long tunnel. After the Second World War, French troops dumped 500 tons of ammunition there, which was supposed to be used to blow up the fortifications of the Siegfried Line. The population of Prüm knew about this storage and was concerned about it.

Source: Wikipedia