An awe-inspiring mosque in Morocco with one of the tallest minarets in the world.

Morocco’s modern capital was once a haven for Barbary pirates, who went so far as to establish a republic of their own.

Thousands of narrow alleyways in an ancient medieval city make up what's believed to be the world's largest car-free urban zone.

The other side is actually green.

Mosaics, storks, and brothels—this ancient city has it all.

The tomb of one of the greatest travelers in history.

Founded as a refugee camp, now a popular tourist spot.

The world's most active stratovolcano is almost always erupting.

A mysterious ancient elephant said to possess magic powers is now the symbol of a Sicilian city.

One of the best-preserved Roman amphitheaters is still used today, but for less brutal events.

Now harmless, this looming post struck fear into the heart of medieval troublemakers.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

Resting in the middle of an Austrian river, this sci-fi "island" lets people cross in neon style.

This one-time health resort was used by aristocrats around the world.

Half-hidden by grassy slopes, this striking Spanish colonial fort is now a museum of underwater archaeology.

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

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

Its sunny hues are believed to have inspired the town's color palette.

An abandoned train station still stands as a testament to the region's industrial and transport history.

No telescopes, no power, no gift shop: The Observatory of Chichen Itza, one of the world's oldest observatories, takes astronomy back to basics.

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

These azure waters were thought to lead to the Mayan Underworld.

If you can look past the nearby sewer pipes, this urban sinkhole grotto is a mini-paradise.

One man's fulfilled dream of living on an artificial island made of recycled plastic bottles.