In Mitte, a district within Germany’s capital once divided by the Berlin Wall, there stands a 32,000-square-foot windowless structure. In contrast to its stark and dense appearance, this unmarked locale has taken on multiple identities. While it was originally built as a Nazi bunker in the 1940s, the space has pinballed over the last 70 years from a Soviet prisoner-of-war camp to a tropical-fruit-storage facility—locally known as the “banana bunker”—and to an ultra-techno club once considered the most hardcore in the world. Today, the bunker’s latest unorthodox iteration propels it, once more, into unexpected territory as one of Berlin’s most prominent art spaces.

Rooted in a culturally rich yet dark history, the bunker was purchased in 2003 by collector Christian Boros and his wife, Karen, who were looking to apply the transformative power of art to a larger, physical space. “From the beginning, Karen and I looked for unexceptional places with historical significance. We wanted an old place that could gain a new meaning and function,” Boros says of the couple’s unique search process, which proved to be less difficult than the subsequent years of renovation.

“The transformation took five years, including unexpected trouble every week,” Boros says of the laborious renovation executed with the help of architect Jens Casper, whom he found while researching German bunkers on Google. The original 120-room compound—made of rock-solid six-foot walls—was torn apart from the inside to create a more open environment, resulting in a unique, multidimensional floor plan to house equally unique works of art. Large-scale installations, including everything from a mock train schedule board to a humanlike horse cutout, both complement and contrast the bunker’s blunt, concrete interior.

Then there’s the building’s figurative icing on the cake: a beautiful glass-enclosed penthouse apartment sitting atop the bunker. This is the manifestation of a lifelong dream for Boros: “I always wanted to live with my art,” he explains.

The first official Boros art exhibition was ready for public viewing in 2008 and has changed every four years since. Boros points out that, with 60,000 people visiting annually, his audience runs the gamut, from “curators and museum directors to political leaders, rap stars, actors, students, tourists, and local Berliners alike.” Like its visitors, the collection is diverse yet consistently contemporary, including work from renowned artists such as Ai Weiwei, Olafur Eliasson, and Andreas Eriksson. In some cases, the couple began supporting these artists before they became internationally recognized. Their approach to the curation process has followed a similar trajectory to their search for a space, disregarding typical rules or conventions of art’s definition and purpose. On a private guided tour, visitors witness this philosophy in action through both the bunker’s legacy and the passion of each featured artist. This makes for a museum experience unlike any other.

Looking beyond the visual harmony and heretical beauty of the Boros Collection, this unlikely combination is also a testament to the city of Berlin—a symbol of its checkered past that represents hope. “We wanted to change a building that once symbolized fear into a destination for liberal thinking. We are fully aware of the history, and we deal with every aspect of it openly,” Boros explains. Instead of ignoring the city’s undemocratic roots, the Boros Collection and Berliners have tackled this history head-on to create a new mecca of art, expression, and diversity. The journey of the Boros Collection is a true reflection of progress, which, according to Boros, is far from over. “Berlin is a city in constant transition, [one that is] never finished. To add something to this ever-changing capital feels fantastic.”