Karen and Christian Boros, in their Berlin penthouse atop the bunker, with Olafur Eliasson’s Colour Experiment No. 10, 2010.

Photographs by Adrian Gaut

When the Berlin collector Karen Boros first visited the place she now calls home, in the late 1990s, she was “catapulted into a different world,” she recently told me. “People were running around in leather outfits and strange masks, and fog machines made it impossible to see.” At that time, the windowless bunker was a fetish-and-techno club with an infamous history: Built in 1942 under the direction of Albert Speer, it was designed as a Nazi bomb shelter. After the war it was used as a Red Army POW camp and, then, as an East German warehouse for storing bananas imported from Cuba. Later it hosted S&M nights and avant-garde performances. In 2003, when Boros, now 54, and her husband, Christian, 51, were searching for a spot for their sizable art collection, the empty, ugly concrete structure in the center of Berlin was for sale. “So we asked our artist friends: ‘What do you think of a Nazi building?’ ” Christian told me when I visited them in Berlin. “And they all said, ‘Of course! To change it with contemporary art would be the best.’ In Berlin, you don’t build a proud signature museum the way Eli Broad or Bernard Arnault did. You change a historical building.”

The Boroses aren’t the only ones who live and work in a landmark building etched with this once-divided city’s multilayered history. On the grounds of the former Crown Prince’s Palace, for example, the curator and artist Nina Pohl has turned a German Democratic Republic (GDR)–era glass octagonal pavilion—once a cocktail lounge and restaurant favored by East German top brass—into a buzzy space for site-specific exhibitions. “An avant-gardist with a great feeling for period style,” as her gallerist Philomene Magers calls her, Pohl lives in the famed Tiergarten, Berlin’s most popular public park, in two connected bungalows designed by the Danish modernist Arne Jacobsen in 1957. Meanwhile, the Chinese dissident artist Ai Weiwei, recently transplanted from Beijing, still works underground, but now in a catacomb-like subterranean brewery-turned-residence-and-studio in the Mitte district. The dealer Johann König, 35, runs his gallery out of a Brutalist former church and lives in its rectory; and, on Museum Island, the gallerist Michael Kewenig and his son, Justus, 28, have transformed a run-down 17th-century town house into an elegant showplace for art by the likes of Christian Boltanski and Sean Scully. Everywhere you turn, it seems, contemporary art is thriving in unlikely spaces. “The reunification was not that long ago,” notes Magers, who moved to Berlin from Cologne in 2008. “You can still find places in the center of the city charged with an energy that gives you a feeling that something happened here. You’d never be able to just claim spaces like these in the middle of New York, London, or Paris.”

Only the Boroses, however, have embraced the challenges that come with making a home and exhibition space out of a former Nazi landmark. “In Berlin there have only been a few large, private collections on display,” says Olafur Eliasson, the first artist the couple consulted about their purchase. “And never one that has activated the gravity of the building’s history the way the bunker has. So they took a quantum step ahead.” To start, the couple had to cut through the roof’s 10 feet of concrete and steel with diamond saws in order to build the glass-enclosed penthouse with skylights. Ironically, the open aerie is their private space, where they live with their son Anton, 12; the monolithic five-floor edifice below is open to the public by reservation, though officially, as Karen put it, “it’s considered a one-family home with a basement.” The Boroses reconfigured that 32,000-square-foot “basement” from 120 cramped rooms into 80 larger ones; still, the effect of walking through the windowless maze is dislocating, to say the least.

A view of the penthouse’s interior.

Photographs by Adrian Gaut

As the Boroses led me through their current show, featuring 130 works by 23 artists, they chatted excitedly about discovering We the People (Detail), 2011, a section of Danh Vo’s replica of the Statue of Liberty, and Klara Lidén’s installation of a teenager’s bedroom, equipped with an emergency ax and a hole in the wall, and relayed how Wolfgang Tillmans spent two days in the bunker installing his early photographs in the many rooms devoted to his work. (Artists are asked to install their own pieces.) The couple change their exhibition every four years or so—their third show opens next spring—drawing on their growing collection of about 780 pieces by 110 artists. Exit arrows in phosphorescent paint, from the war years, are still visible on the walls. On tours, bits of history invariably trickle out, such as the time a visitor recounted that she was born in the bunker during an air raid. Another confessed he was conceived there. “The art is always fighting against the architecture,” Christian said when we stopped before Ai Weiwei’s twisting, 20-foot-tall driftwood Tree, 2009–2010, which intentionally looked stunted by its setting. “You are alone with the art, and it’s hard work.”

For the Boroses, collecting is a way to ground themselves in the present. “I love art that I don’t understand, because then I can learn my limit and extend it,” Christian told me as we sat at their dining room table eating the open-faced venison sandwiches that Karen had prepared. Both were the picture of art-fair chic: Karen, in a checked Prada top and Margiela cardigan that set off her blue eyes; Christian, in a black Prada jacket, crisp dark shirt, and jeans. He pointed to the two early paintings by Elizabeth Peyton resting on a sideboard, and to the large Ventilator, 1997, by Eliasson, whose work he has collected since the artist was a student. “The first time I saw Peyton, I thought it was girls’ art,” said Christian, who now owns 40 works. “Why so small? Why so beautiful? Then with Olafur, I said, ‘Is it about science?’ So for me it’s about learning and fighting against my grid and having conversations with artists.”

The Boroses are lively company and keen raconteurs. Since 2005, Karen has headed German VIP relations for Art Basel, while managing a family-owned real estate business. She trained in art history and psychology in Australia and Germany, where she worked at Philomene Magers’s former Cologne gallery. The Polish-born Christian, an advertising mogul and art-book publisher, immigrated to Germany from Communist Poland at the age of 6 with his family. At 18, when his struggling parents generously gave him 4,000 marks for a car, he instead bought Joseph Beuys’s Pala, a shovel that was part of the artist’s expansive reforestation project 7000 Oaks, begun at Documenta 7 in 1982. For a time, Christian studied aesthetics and wrote on a subject that still obsesses him: the villains of James Bond, who would no doubt fancy Mr. Boros’s lair. Eventually, he pursued graphic design and advertising, and it was partly by chance that he discovered the so-called Young British Artists generation. In London in the early ’90s, he bought three paintings from Damien Hirst for 10,000 pounds after befriending him at a bar. He went on to collect works by Tracey Emin and Sarah Lucas, among others.

Karen Boros, with three of the 40 paintings by Elizabeth Peyton in the couple’s collection.

Photographs by Adrian Gaut

Meeting Karen at Art Basel in 1998, however, turned him into a bona fide collector. “She radicalized me,” he said, as he worked his way through a pack of Lucky Strikes. “More. Bigger.” Back then she was a specialist in Ed Ruscha at Sprüth Magers, and, to impress her, he bought a Ruscha on display in the booth, though he didn’t much care for it. (It now hangs over their bed.) These days the pair collect only the work of artists they like on a personal level and only buy pieces produced within the past year. Art advisers need not apply. ‘’We don’t outsource our passion,” Karen said, simply. Christian elaborated: “For us, it’s like hiking a mountain: You can take a helicopter to the top or you can walk by yourself. Of course, we make mistakes—but they are part of our history.”

A quick glance around their enormous open-plan penthouse, with its wraparound terrace, minimalist outdoor garden, and reflecting pool, hints at the taste that informs that history. Inspired by the architecture of Mies van der Rohe, it was designed by Jens Casper, a then-student architect the couple discovered on Google after they typed “bunker architecture” and an essay he’d written on the subject popped up. Many of the doors are lined with calf leather, and the only room without concrete is made of wood from a single 500-year-old oak tree. In the living room, below a multitiered cascading Venini chandelier of Murano glass, sits a Hans Wegner Papa Bear chair from the ’50s and a stone Ming dynasty tea table. On a sitting room wall, the bare-breasted Virgin nurses the Christ Child in a Northern Renaissance painting that purportedly once belonged to Pope Leo X.

A view of the penthouse’s interior.

Photographs by Adrian Gaut

Berlin’s local collector base remains small compared with that of New York or London, and the galleries, artists, and institutions that make up the city’s pulsing art scene are integral to the couple’s world. They recently purchased an important Bauhaus building from 1928 that they converted into studios for young artists, and are regulars at the cutting-edge shows of sculpture, performance, and media art curated by their friend Pohl at the Schinkel Pavillon. Built as a GDR monument in 1969 by the East German architect Richard Paulick, the pavilion “is a collage of art and architecture—a rebuilding from the ruins,” Pohl told me the day I met her there. Pohl, who was wearing a black rabbit jacket, transmits a kind of haphazard glamour. Her lips are usually painted bright red, and she wears her jet black hair long, with Bettie Page bangs. She was in the midst of installing a collaborative exhibition by the artist Shahryar Neshat and the choreographer Adam Linder, and the octagonal room’s floor-to-ceiling glass windows were covered with pink gels, casting a lurid neon glow on the historical landmarks surrounding it. From each angle, one glimpsed a different era—the towering neo-Gothic church by the architect Karl Friedrich Schinkel; the pseudo-19th-century town houses abutting it; and the reconstructed Crown Prince’s Palace, which, in 1918, housed a museum of contemporary art.

The pavilion was empty when Pohl discovered it in 2007, the year she arrived in Berlin from Düsseldorf, where she had lived with her husband of 14 years, the artist Andreas Gursky. Immediately she wanted to revive its ties to contemporary art. By inviting emerging and established artists to wrestle with its quirky shape and setting, Pohl has helped the experimental nonprofit Schinkel Pavillon earn its near-cult status among the art crowd. To prepare for its 10th anniversary next summer, she just opened a performance space–cum–club on the ground floor. “She’s created something that’s very influential and mesmerizing,” the Berlin gallerist Tim Neuger says. “And she raises the money herself and convinces the artists.” So far, the roster has included more than 65, among them Isa Genzken, Camille Henrot, and Thomas Hirschhorn, who deconstructed the pavilion’s ceiling so that it appeared to be crashing in.

Steeped in art since childhood, the Berlin-born Pohl moved to Düsseldorf when she was 4. Her father was an architect and her mother, a stylist and fashion designer whose Pohl + Benzenberg label riffed on Jil Sander and other chic minimalists. When Pohl was in her teens, in the ’70s, her mother began a relationship with the painter Sigmar Polke that lasted several years. There were lots of drug-fueled parties at Polke’s farmhouse nearby, and summer vacations in Spain with Polke and fellow painters Albert Oehlen and Martin Kippenberger. “It was really wild,” Pohl said, recalling that she grew especially close to Kippenberger, from whom she won several drawings playing cards. Though he inspired her, she said, “even as a chaotic teenager, I knew he was very intense.”

The artist and Schinkel Pavillon curator, Nina Pohl, with her cat, Olmo, in her 1957 Atrium house, designed by Arne Jacobsen and set inside Tiergarten park.

Photographs by Adrian Gaut

At 25, she had just completed her studies in photography and film at the famed Folkwang University of the Arts, in Essen, when she met the 39-year-old Gursky, whom she would marry in 1995. “He was at the beginning of his career and wasn’t yet known,” she said. “We talked about everything during our marriage. The pictures he became famous for, we did together.” Pohl’s own large-format works play with the boundary between photography and painting and the concept of reality associated with photographic images. She still calls Gursky, now her ex, her most important influence, and a landscape he made hangs in her Jacobsen bungalow. Closed off from the street, the 1957 Atrium house, one of the few residences in the Tiergarten park, opens onto a garden. Pohl kept the original palette of mint green and teak but added a terrazzo floor and personal touches like two shaggy pink sofas by the Campana Brothers and assorted midcentury finds. On the day I visited, workmen were busy connecting the bungalows. “Everything is crazy, because it’s the same house twice,” she said, laughing. “One is a mirror of the other.”

You couldn’t get further from Pohl’s funky modernism than the stately Kewenig Galerie, a family enterprise situated in a 1688 town house, one of the oldest residences in Berlin. Kewenig opened in 2013, following an almost 30-year run in Cologne, where it was founded by husband and wife Jule and Michael Kewenig. In earlier days, he had worked as an assistant to the Cologne dealer Rudolf Zwirner (David’s father) before launching a brief career as a lawyer; she had inhabited the art world as the wife of the painter Markus Lüpertz, and then the dealer Michael Werner, who remains a close family friend. It was their son, Justus Kewenig, who spearheaded the move after discovering the GDR ruin and overseeing its painstaking rehabilitation. Now there is a glass elevator, a grand hand-carved oak staircase, and elegant, airy rooms that were filled with toilets and showers when Justus first saw them. While Jule operates the Kewenig outpost in Palma de Mallorca, Spain, Justus and his father oversee Berlin, which includes a humongous warehouse and exhibition space in a 19th-century transformer station. (It will open this fall with a show of new work by the Arte Povera master Jannis Kounellis.) And in October, the collector Désiré Feuerle will officially debut the Feuerle Collection, a private museum in another bunker, located near the Brandenburg Gate and renovated by the British architect John Pawson. There, Feuerle plans to juxtapose selections from his collection of Chinese furniture, Southeast Asian sculpture, and contemporary art.

Installation view of Jorinde Voigt’s 2016 exhibition “Radical Relaxation,” at the Konig Galerie.

Photographs by Adrian Gaut

For their part, the Boroses are far from done rehabilitating disused spaces. These days, Christian’s offices occupy a former sewage pumping station built in 1878 that was a ruin when he bought it from the city in 2009. (By that time, it had become a lapidarium for public monuments rescued after the war.) Their latest project combines art, living, and nature across 11 buildings that comprise the rural compound they are building, brick by brick, 33 miles north of Berlin. There were only basements on the land when they purchased it; “What to do?” Christian asked. “I want to live in an old country house, but there aren’t any. So I began buying entire houses and buildings—the stone, the wood, everything.” On his laptop, he pulled up a few of the e-mails he gets daily offering him old walls from Poland and other spots. Floor pieces by Carl Andre and commissioned installations from Eliasson will be the only traces of urbanity.

Initially there was a hitch: The land could not be sold unless the endangered bats native to the area were promised protection. So Christian hatched a plan: “I built them a bunker,” he told me. “Another bunker! It goes 26 feet into the ground. And now the bats have a place to live.”