Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

One of the smallest bookstores on the planet.

This head-spinningly bizarre Depression-era art cave is wall-to-wall quartz and Jesus.

Ring the bell to enter a bar that looks equal parts museum and old curiosity shop.

Once a year in Pomuch, the dead are taken out for a cleaning.

This one-of-a-kind convent boasts a kaleidoscopic exterior of stars and double-headed eagles.

A sprawling network of century-old subterranean catacombs lies beneath a nondescript suburban home.

A magical sinkhole on the Yucatán Peninsula is adorned with mini waterfalls and hanging vines.

Three sinkholes filled with warm, crystal-clear water reached by a horse-driven cart on an old train track through the jungle.

The meteor that sealed the fate of the dinosaurs landed at this site, one of the largest impact craters in the world.

It would take you approximately an hour and a half to walk to the end of Mexico's largest pier.

One of the few places where you can visit a cenote and Maya ruins at the same time.

Iconic red and white plaques show the creative names invented to navigate the city streets.

The largest Neolithic ruins in the world hide a notably clean prehistoric metropolis.

The deepest underground city in Turkey was designed to protect 20,000 people behind massive stone doors.

While not Turkey's deepest underground city, this subterranean redoubt is the largest.

This ancient subterranean megalopolis is known for the hot oil traps that were installed above each of its entrances.

The ornate miniature mansions were built for Istanbul's feathered residents.

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

This airport also offers travelers the chance to view thousands of years of Turkish history.

This eatery re-creates dishes from the Ottoman Empire so you can dine like a sultan.

Hidden just under the waters around this Turkish island are the ruins of a once great city.

Flames have been burning within this mountain for more than 2,500 years.