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.

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

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

This modest marker near Notre Dame identifies the very center of Paris.

An ethereal glowing blue ocean cave in Croatia.

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

The ancient mosaics here are considered among the finest in the world, and serve as a stunning record of Greco-Roman daily life.

There was a top secret plan during World War II to seal a group of soldiers inside the rock.

Single runway interrupted by a busy road that cuts across its middle.

This London pub hides a peculiar secret: a recreation of the rooms shared at 221b Baker Street by Sherlock Holmes and Dr. Watson.

This artificial archipelago was supposed to resemble a map of the world.

This indoor ski resort has a mountain contained inside a mall.

A preposterously luxurious hotel with gold-plated iPads, Rolls Royce chauffeurs, and a staff that trains by watching "Downton Abbey."

On any given day this sprawling market houses literally tons of government-regulated gold, gems, and precious metals.

This futuristic building is yet another architectural wonder in Dubai.

This enormous sports car themed amusement park is home to the world’s fastest roller coaster.

Whitewashed mosque contains the world's largest carpet.

The ancient latrines of the Greeks, in all their public glory.

This colorful and quirky set of pegasus sculptures celebrate the works of poet Zbigniew Herbert.

An artificial date palm stands as a memorial to Warsaw's Jewish community.

The giant statue and its model solar system honor the native Pole who declared that the Earth revolves around the Sun.

The Polish capital has had a deep connection to its guardian mermaid for almost a millennium now.

A statue honors the children who fought Nazis in Poland.