[SOFIA, Bulgaria] Every day for the past 20 years, Lyudmil Kutev has lumbered three stories down the crumbling concrete steps of his Sofia apartment, descended into a basement Cold War bunker packed floor to ceiling with shoes, and swung open a rusty window panel just inches from the sidewalk.

"My father hid here during the Allied bombing," Kutev said, polishing a pair of loafers in the cramped space and peering up at the feet of those passing by outside. "And in the last years of communism, he hid this shoe-repair business down here, too." Below Sofia's Ottoman mosques, Red Army monuments and onion-dome churches, some of the most intriguing relics of this city's tangled past lurk below the sidewalk - and you'll have to crouch down and peer through tiny windows to find them.

Known as klek, or squat, shops, these knee-high ateliers and stores are nestled in former storage cellars and bomb shelters, and they're found only in Bulgaria's capital. Today, as a record number of tourists visit Sofia, these squat shops are emerging as some of the city's most creative underground spaces.

"Visually, kleks are incredibly unusual, interesting spaces," said Iara Boubnova, director of Sofia's Institute of Contemporary Art. "The fact that they force you to bend down and shift your perspective offers so much artistic potential." In recent years, the institute has put on two pop-up exhibits inside kleks, and Boubnova is showing a new klek-inspired video installation through May 31 beneath Eagle Bridge.

Before World War II and during the Cold War, Bulgarians and Soviets designed bomb shelters in basements throughout Sofia. The rooms lining the perimeter often had a small window just above street level.

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As communism unraveled in the late 1980s, many residents lacked money to open independent shops, so entrepreneurs started illicitly selling extra appliances and household goods while craftsmen offered shoe repair, tailoring and other services to pedestrians from their dimly lit bunkers. By the 1990s, there were underground squat shops on most every street in Sofia.

"These 'kleks' were actually among the first private businesses in Bulgaria," said Angel Bondov, an urban planner who conducted the first government-funded study of Sofia's kleks this past January. "They symbolise our creative shift from communism to capitalism." Yet, as more chains and supermarkets have opened downtown, these reminders of Sofia's early can-do capitalist spirit are vanishing. According to Bondov, more than half of the city's kleks have disappeared since 2012, with only 27 remaining today. In their place, a wave of artists and entrepreneurs are transforming these spaces into studios or speak-easies, while some surviving kleks are evolving from hole-in-the-wall stores to incorporate a modern, locavore twist with local, natural food and drink.

Wander through central Sofia today and you'll see older shoppers in flappy Russian ushanka caps and post-Cold War cool kids crouching to buy Bulgarian chocolates, bold-red wines from the Thracian Valley, and hand-painted cooking pots from Troyan. Merchants often display their inventory in glass-covered shelves where the sidewalk meets the building, while others pump upbeat Bulgarian pop folk chalgra songs from their spaces to draw the attention of those above.

Across from the National Palace of Culture park, visitors peek down at Petranka Pedrova's klek bakery, which like most of the other kleks has no formal name and is known to locals as Fornetti. Customers can choose from 32 freshly squeezed fruit juices - from local apricots to imported kiwis - to pair with her flaky banitsa phyllo dough pastries.

Near the Ivan Vazov National Theater, Radoslav Alexandrov tops the toasted ground-beef and kashkaval cheese princessa sandwiches at his klek, Filiite, with chopped chubritza herbs from his garden. Thirsty? Ask for minty tea made from a boiled bouquet of plants Alexandrov picks from Bulgaria's Rhodope Mountains.

"Here, my monthly rent is 200 lev" (or S$167), Alexandrov told me as I squatted on the sidewalk looking in. "Above ground, it might be 2,000." After leading me on a three-hour tour of squat shops, Kristian Mitov, the founder of Sofia's Balkan Bites tour, pointed down a flight of stairs from the sidewalk into a building cellar. "Young people have started adding entrances to convert former kleks into basement galleries," he said.

Perhaps nowhere better exemplifies the trend of breathing new life into Sofia's bunkers than 5L, which became Bulgaria's first speak-easy when it opened in February 2017 just off the increasingly trendy Shishman street. After selecting the right key to open a hidden door, patrons go down two floors into a vault enforced with 2-foot-wide stone walls and a concrete ceiling. A menu mapping an "Evacuation Plan" nods to the space's former use as a bunker and highlights an encyclopedia of fruity Balkan rakia brandies and ouzos that the mixologist Darko Angeleski blends into cocktails.

"Kleks, basement businesses and speak-easies all started as these hidden, illegal things," Angeleski said. "I want to show locals something familiar and then surprise them."

NYTimes