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

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

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

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

This unreal Portuguese palace looks as though it's made from a pile of different castles.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

Over the centuries, this island paradise has done it all, from providing monks with ecclesiastical respite to sheltering an exiled Leon Trotsky.

The legendary luxury train passage is commemorated with a charming museum inside its former eastern terminus.

1513 Turkish world map, full of European state secrets and snarky commentary.

Ancient serpentine sacrifice holder that has stood the test of time.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

Five sultans and their families rest in eternal splendor, teeming with overlooked beauty and drama.

A marvel of Byzantine engineering under the streets of Istanbul.

Raging waters have created a strange geological site that looks like something off of a progressive rock album cover.

The world's highest and most dangerous infinity pool lies at the precipice of Victoria Falls.

Largest cave system in Africa.

Metro station with a claim to rock n' roll fame.

Berlin's old airport.

Cold war icon and onetime "hole" in the iron curtain.

Blitzkrieg bop your way through Berlin's Ramones Museum.

A giant scale model giving a sneak peek at what urban planners see for Shanghai by 2020.