A collection of 20th-century automata, penny arcade games, and musical contraptions.

Aqueducts have dramatically changed this old lake, now home to tufa towers and its very own species of tiny brine shrimp.

This naturally heated mountainous creek has created a group of neon blue pools of potentially deadly boiling water.

The lowest point in North America is home to an undrinkable pool surrounded by fields of geometric salt flats.

Millions of years of oxidation make a drive down this winding Death Valley road surprisingly colorful.

A tunnel with windows, so you don't miss out on the impressive views.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

Site of the largest volcanic eruption in the last 25 million years, one which may have nearly wiped out humanity altogether.

One of Indonesia's tallest, this waterfall takes a 390-foot plunge into the Lake Toba caldera.

The fifth-longest natural arch in the world, and the longest outside China.

The location where the iconic movie character declared it was time to go home.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

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

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

Elaborate tile work in this railway station tells the story of Portugal.

This restored Portuguese cafe may well be the most beautiful place in the world to grab a Big Mac.

This giant sculpture made of trash is a critique of society's wastefulness.

The largest and best-preserved Roman amphitheater in Africa was designed to seat 35,000 people.

Taking the subway here means doing so over a bridge located in the middle of an estuary.

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

A marvel of Byzantine engineering under the streets of Istanbul.

The first skyscraper to include a Ferris wheel built into the facade.

A literally moving statue of stacked metal giants just continually trying (and failing) to find love.

Tower with a double-helix spiral, adorned with letters of the Georgian alphabet.