One of the new seven wonders of the world, the ancient city of Petra was once the capital of the Nabataean kingdom between 400 BC and AD 106. Carved into the red sandstone cliffs in a southwestern corner of Jordan, Petra's extraordinary buildings were 'lost' to the Western world until the early 1800s, according to National Geographic.

Many of the stone structures – such as the Treasury, pictured – are simply façades hiding relatively small burial chambers inside, leading early explorers to conclude that Petra was a puzzling city of tombs.

While tombs such as this one do form part of Petra, modern findings point to a lively city with elaborate terraced gardens, pools, spas and villas, according to Smithsonian Magazine. A grand free-standing temple complex with a 600-seat theatre is just one of the discoveries suggesting that Petra was a thriving trade centre, which flourished for almost 1,000 years.

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