The sunken structure looks like the victim of a catastrophic flood.

This ancient theater was once the home of fierce gladiatorial battles.

A series of abstract, silly sculptures represent the works of a great modern classical composer.

This ancient Roman bridge and aqueduct still stands as a wonder of classical construction.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

This salt marsh in Southern France is as pink as the flamingos that inhabit it.

A Gothic cathedral created from volcanic rocks.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

These Australian rock formations look like Martian beehives that have grown up out of the landscape.

This trio of Australian rock spires may have inspired aboriginal legend or just modern tourism.

Alien rock formations grown from the sands of an Australian national park.

An opal mining town in the middle of Australia where people live, worship, and shop underground.

A massive stairway that almost wasn't leads to one of Australia's most scenic vistas.

Ruined 11th century abbey built by King David I in Edinburgh, Scotland.

Near the former site of numerous witch burnings, this lavish Edinburgh mainstay pays homage to Scotland's brutal history.

17th century streets hidden under Edinburgh were once a breeding ground for the black death.

One of England's oldest stone churches and the birthplace of the "father of English history."

Follow the original medieval paths that wind through this intriguing section of the city.

This network of narrow, medieval passages has the most delightful name.

J.R.R Tolkien, C.S. Lewis, and other "Inklings" met at the Oxford pub to discuss the now legendary fantasy stories they were writing.

Used as an example in one of the first dictionary entries for "museum" in 1706.