At 58 metres tall - just a little taller than the Leaning Tower of Pisa, but with considerably more heft - the St Pauli bunker in Hamburg, Germany, has dominated the city skyline for more than 80 years since it was built in World War II under the Nazi regime. Built this concrete hulk has had a surprising rebirth. The relaunched Hamburg Bunker is now packed with two restaurants, a five-storey Hard Rock Hotel and a newly built pyramid-like rooftop bar and garden.

The hotel has the kind of modern details you'd expect in any self-respecting hip hotel, such as self check-in, smart technology and co-working spaces. Bar-restaurant Karo & Paul opened as a bar in April and occupies the first three levels of the building. The restaurant area is still coming soon.

On the fifth floor is the restaurant La Sala – Spanish for living room - offering lofty views. The Hamburg bunker was one of eight flak towers – above-ground anti-aircraft bunkers which doubled as air raid shelters - which Germany built after British air raids on Berlin in 1940. Following the end of World War II, Germany was eager to shed all signs of the former Nazi regime, but this 76,000-tonne concrete behemoth with walls 2.

5 meters thick can't be easily demolished or ignored. Civilians were initially accommodated in the building during Germany's postwar housing crisis. The space was later used by a German TV station and other businesses.

Since the 1990s, it has become known as the "media bunker," housing around 40 orga.