An abandoned textile factory on the "island of crows" was home to Estonia's first workers' strike.

A secluded art gallery hidden within the cellars beneath Tallinn’s medieval monastery.

The widest waterfall in Europe is a natural wonder and one of the only places where fish are caught in the air.

The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

One of the shortest streets in York has an especially odd name.

This bustling Italian plaza is built on the ruins of an ancient Roman amphitheater.

The marble facade hides a little-known medical museum with early surgical instruments and rare copies of canonical texts.

The medieval prince founded the first library in Ukraine at Saint Sophia's Cathedral where he was interred.

A curious little museum dedicated to the furry feline in the cat haven that is Old Town Kotor.

A whale rib was used to advertise the store by the arch that offered exotic goods from far away.

Where Venice's gondolas go for a tune-up.

In this Parisian garden's grotesque former life as a zoo it fed exotic animals to the bourgeois and put humans on exhibit.

This unusual piece of Renaissance art depicting the bodily horror of crucifixion and skin disease may have been inspired by fungus-induced hallucinations.

People have been living in the cave houses on this Italian hillside since the Neolithic era.

Africa's Venice on stilts.

These "50 Fortresses" have been unearthed in the ancient oasis of Khwarezm.

Light still pours into the ruins of this ancient Islamic observatory.

The Avenue of Mausolea is a series of grand palatial tombs.

An 18-meter-long sarcophagus of a constantly growing dead prophet.

This "tower of death" has acted as an observatory, a religious hub, and an executioner's lair.

A medieval church with largest and oldest collection of Renaissance frescoes in France.

An extensive collection of reliquaries containing the bones of saints housed in the largest Catholic church in Venice.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.