If you can’t tear it down, renovate it.

A massive former Nazi bunker in Germany that was deemed too complex to demolish has been transformed into a luxury hotel hub filled with restaurants, a concert hall and a rooftop terrace.

The five-story structure in Hamburg’s St Pauli district has loomed over the city for decades as one of the largest bunkers in the world with a dark history tied to the Nazi regime.

Now its gray, concrete roof has been topped with greenery as part of a five-year, $100 million renovation project that includes a 134-bedroom hotel, a 2,000-seat concert hall and a community garden for locals to enjoy, the AFP reports.

“The idea of raising the height of the building with greenery was to add something peaceful and positive to this massive block left over from the Nazi dictatorship,” said Anita Engels from the local Hilldegarden neighborhood association.

Bunker St. Pauli, a Nazi structure deemed too complex to demolish, has been converted into a luxury hub in Hamburg. dpa/picture alliance via Getty Images

The renovations include a 134-room hotel. dpa/picture alliance via Getty Images

During World War II, the Nazis built the St Pauli bunker in 1942 as a series of massive “flak towers” that served as shelters during air raids, as well as propaganda for Hitler’s rule over Germany.

Two Nazi-era bunkers were built in Hamburg, three in Berlin and three others in Vienna. All remain standing today except for one of the Berlin structures which was demolished due to safety risks.

Officials have warned that the explosives required to take out the bunkers — which have exterior walls more than 8 feet thick and a roof consisting of 11.5 feet of reinforced concrete — would pose too big a risk for the heavily populated areas.

The St Pauli complex held up to 25,000 civilians during the July 1943 Allied bombings of Operation Gomorrah, which left the city of Hamburg devastated.

The gray, concrete structure stood as a sore spot for the people of Hamburg. ullstein bild via Getty Images

The structure was built in just 300 days in 1942 and used to shelter people during Allied aerial raids. ullstein bild via Getty Images

After the war, Bunker St. Pauli was used to house the homeless in Hamburg before being transformed into office space for a TV broadcasting center and advertising companies in the 1950s.

The lower floors eventually became venues for musicians and the nightlife scene, while other sections housed a radio station and even a climbing gym.

By 2019, the city of Hamburg and private investors launched the renovation project to fully transform the bunker — as part of a new “deNazification process,” according to the property’s website.  

The renovated building includes several new restaurants. dpa/picture alliance via Getty Images

A trendy bar is also operating inside the former Nazi bunker. dpa/picture alliance via Getty Images

The proposal came a year after the headquarters of the Gestapo, the Nazi’s secret police, reopened as a luxury space housing boutiques, offices and apartments in Hamburg.

The city previously transformed its other flak tower into a mini power station that produces electricity from renewable sources.

While Germany and Austria continue to tackle the issue of renovating Nazi structures for modern-day uses, the St Pauli will memorialize its past with a museum exhibition located on the first floor.

Hamburg residents will also have access to a community garden that now tops the building. dpa/picture alliance via Getty Images

As renovations were underway, the Hilldegarden neighborhood association collected testimonies from people who lived at the bunker during the war.

The group also tracked down the records of those who were forced to build it within the span of just 300 days, with their stories now available for viewing at the exhibition site.

Along with the two Hamburg towers, German officials transformed the two remaining bunkers in Berlin into two city parks after burying them beneath artificial hills.

One of the flak towers in Vienna was renovated into a 43,000-square-foot public aquarium.