A stone age atrium
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If 'MTV Cribs' had traveled back in time 70,000 years, this skylit space is just the kind of Paleolithic pad they'd have toured. Archaeological evidence suggests Devetàshka Cave, in modern-day Bulgaria, housed human denizens from the Middle Stone Age until at least 6,000 BCE. After its rediscovery in the 20th century, Devetàshka was unceremoniously repurposed as a military warehouse, but was soon given back to nature. Now a protected site, this karst cave's days of human habitation are probably over. But it's home to a bustling crowd of another kind: Some 30,000 bats make their home in the cave's depths.