LITERATURE REVIEW

2.2.4.

Famed for its cameo in the film “Indiana Jones and the Last Crusade,” Petra is an ancient caravan city tucked away in the mountains of southern Jordan. The site has been inhabited since prehistory, but it reached its peak some 2,000 years ago when the ancient Nabataeans handchiseled the surrounding sandstone hillsides into a dazzling collection of tombs, banquet halls, and temples. One of the most exquisite edifices are Al Khazneh, or “the Treasury,” which includes an ornamental façade that extends 130 feet up a rock face. Petra may have been home to 20,000 people at its height, but it was later abandoned sometime around the seventh n century A.D. and was not known to Europeans until the 1800s. Excavations at the site are still ongoing today, and it’s believed that the vast majority of its ruins may still lurk underground.

2.2.5.

In the 1960s and 70s, as the threat of nuclear war loomed, the Chinese government ordered the construction of a mammoth fallout shelter beneath their capital of Beijing. Also known as Dixie Cheng, the hand-dug site was capable of safeguarding around one million people for up to four months. It consisted of falloutproofed rooms and tunnels that snaked their way underground over an area of several dozen square miles. Certain passageways were large enough for tanks to pass through, while others housed purpose-built schools, hospitals, granaries, and restaurants. There was even a skating rink and a 1,000-seat movie theater. While the Beijing bunker was never used, its decaying tunnels still exist corridor beijing today, hidden beneath the city’s homes and businesses. Most are sealed off, but they were briefly opened as a tourist attraction in the early 2000s.

2.2.6.

Also known as the “Underground Salt Cathedral,” Poland’s Wieliczka Salt Mine is a massive subterranean complex of rooms, passageways, and statues located on the outskirts of Krakow. The site dates to the 1200s when miners first descended beneath the earth’s surface to find rock salt. In the centuries that