The only swimming pool listed on the National Register of Historic Places is emptied and refilled each day with naturally filtered water.

An ancient and majestic fortress that played an integral role in Portugal's road to independence.

America's only city hall with minarets took architectural cues from Ali Baba and the Forty Thieves.

When you can't get to the Pacific, just go to Florida.

This stunning concert hall has become a symbol of Iceland's national recovery.

This metal tower in the desert provides views of a handful of Nazca geoglyphs.

A set of ancient drawings in the desert of Peru that are so massive, many of them can only be fully seen from the sky.

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

A well for a well, this anachronistically Indian-styled water pit was built in its small town home in gratitude for a similar favor.

The intended purpose of this unfinished Elizabethan building remains a mystery.

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

The drama of nature in full effect in this Nevada State Park.

The gorgeous entrances into the city's underbelly look more like grand halls than subway stops.

Clap your hands at the base of the pyramid, and the song of a sacred Mayan bird will echo through the air.

The reconstruction of this prominent building fulfilled a long-written command.

The oldest continuously operating pharmacy in Europe.

An encyclopedic collection of mammal penises.

Known as the "Valley of the Moon," this Jordanian wadi is one of the most amazing desertscapes on Earth.

This elegant arc of a waterfall marks a religious turning point.

The picturesque birthplace of Icelandic democracy is drenched in the blood of its brutal past.

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

The most powerful waterfall in all of Europe.

This valley of hot springs and boiling mud pots is home to the record-holding "Geysir," which originated the English word.

Iceland's largest lagoon is home to stunning multi-colored icebergs.