The 1940s air raid shelter in Hamburg’s St. Pauli district has been reimagined as a “green mountain,” with expansive gardens covering the top of the wartime structure. Known as the “Hochbunker,” the site has undergone an extensive restoration and redevelopment process that has seen the creation of restaurants, event spaces and a hotel, as well as a rooftop urban park. The bunker will open to the public on July 5, 2025, with the goal of reconnecting the community with the iconic structure and its complex history.
This flak tower was originally built during World War II on the orders of Adolf Hitler and served as a defense against air raids. Completed in 1942, the concrete structure was designed to accommodate up to 18,000 people and had wide entrances for women with strollers and children. Measuring 75 by 75 meters wide and 35 meters high, the structure has been an important reminder of Germany’s wartime past for over 80 years.
Due to the strength of the structure, demolition plans were quickly scrapped as the process would likely damage the surrounding residential buildings. Since then, it has been used for various purposes. The most recent restoration efforts were initiated by the local residents’ association Hilldegarden eV, which ensured the documentation of the bunker and initiated public participation in the transformation process, as community members interested in contributing to the memorial or urban garden initiatives can contact the non-profit group.
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One of the highlights of the project is the roof garden with panoramic views of Hamburg and a winding “mountain path”. A total of 80 sensors installed in the green area will measure the impact of green roofs and facades on the microclimate. This sustainable irrigation system and planting concept – with 4,700 plants – is intended to prevent flooding and promote biodiversity, positioning the bunker as a model for climate-resilient urban spaces. The bunker will also be expanded to include a memorial for Nazi victims and provide space for local culture, art exhibitions and events.
Because of its visually striking presence, the project draws parallels with notable structures such as New York’s High Line. Nevertheless, restoring its historical significance has been given the highest priority. Similar projects have gained traction around the world, such as EUROPARC’s redesign of the European Parliament building in Brussels, Belgium, or the ongoing proposals to redesign Paul Rudolph’s brutalist Government Service Center in Boston.
