This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

Monasteries on rock pillars, once accessible only by frayed ropes.

The hallucinogenic center of the ancient world.

The famous artist couple lived and worked here, in two different houses connected by a bridge.

A gorgeous, Gaudí-esque stairway constructed in the city of Istanbul by a prominent Jewish family.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

Legend says if you stick your thumb in the hole and it gets wet, your wish will be granted.

This 23-foot-tall bear stands amid the hustle and bustle of Hamad International Airport.

The enormous diamond-shaped building packs a trove of academic and literary treasures into one futuristic space.

This fountain pays homage to Qatar's history of pearling, the primary industry before oil.

This spectacular mosque houses the second-largest chandelier in the world.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

Eighty million natural history specimens call this gargantuan museum home.

A "simple-hearted artist" turned an isolated Icelandic valley into his own art museum.

If a glacial river suddenly diving into a sheer chasm via a dramatic, multi-stage waterfall isn't peak Iceland, it's certainly close.

Strange rock formations tower above the river that snakes through this enchanting Icelandic canyon.

One of the tallest buildings in Iceland, and perhaps, the most visually impressive.

The official motto of Luxembourg reminds passersby of the Luxembourgish commitment to their national identity and sovereignty.

Two geological phenomena in one precarious locale: a towering stone window, and a deep blue void.

One of Malta’s most popular beaches features a seemingly out-of-place statue of the Virgin Mary and baby Jesus.

This 19th-century aqueduct provides insights into how water was supplied to Victoria on the island of Gozo before modern plumbing.

These clocks tell time in a theological sense.

This church is named for one of the most dramatic tales in the early Christian church.

The fishing boats that moor in this small lagoon enter and leave through a tunnel to the sea.