Cannerberg is a hundred-metre-high hill spread between Riemst in Belgium and Maastricht in the Netherlands. The slopes turn green thanks to the Canner and Millennium forests, but it is mainly what goes on underground that draws attention. 

Marl quarries

For centuries, the hill has been riddled with tunnels, passages and shafts of the underground quarries where limestone was mined, so-called Limburg marl. One of those limestone quarries, Groeve Bosberg in the Netherlands, was given a completely new lease of life during the Cold War.

NATO command centre

In 1955, an ultra-secret headquarters of NATO (the North Atlantic Treaty Organisation) was built in the underground maze of eight kilometres of corridors. During the heyday of the Cold War, the bunker was manned day and night by hundreds of Belgian, Dutch, German, British and American military personnel. The command centre remained there until a few years after the end of the Cold War. In 1992, it was over and done with.

Even before the command centre closed its doors, asbestos fibres were found in air samples. Hence, the entire complex was completely gutted from 2003. 

Stripped

Tours of the underground complex are organized since 2013. Hardly any traces remain of the NATO command centre, due to the thorough remediation, but guides bring the Cold War story back to life during a two-hour walk in the quarry.