Fears of Satanic worshippers swirl around five Celtic-inspired megaliths.

This unique structure allowed boats to bypass underwater mine barriers in the channel to enter the harbor.

A thorough look at the development and history of the underground's rolling stock of the Madrid subway system.

This pair of unsuspecting buildings are in fact the very first modern skyscrapers in Europe.

A memorial in the Tiergarten is a reminder of the suffering inflicted on homosexuals by the Nazi regime.

A monument to the three wars that led to German unification towers within a Berlin traffic circle.

A 19th-century perch for spotting sailing ships now boasts one of the most iconic views in the Southern Hemisphere.

Hidden within Sydney’s lush Royal Botanic Garden is a walled cactus rockery and the site of Australia's first zoo.

A statue of a Scottish cultural icon in central Sydney.

This Masonic lodge was the first major private building to be constructed in Washington, D.C. after the Civil War.

The National Park Service’s best-kept secret with views that rival any in D.C.

This bridge over D.C.'s Rock Creek Park is sometimes called the "Buffalo Bridge" because of its four buffalo sculptures, which were cast from a single piece of bronze.

A city park that sits on top of a freeway.

Dedicated to the man who created the first radio wave communication system.

A brass and marble scale model of the solar system embedded in the concrete.

Watch cheese-flipping robots in action at this factory and museum.

Locals dubbed it the "Owl Building" because of its bird-like appearance.

Campus tradition says couples who walk beneath this enormous oak will stay together forever.

Decades of discarded bottle caps line this alleyway, a fixture of Texas A&M.

Official museum, hall of fame, and repository of the Texas Rangers.

This former Texas landfill is flush with 300 million-year-old fossils, all fit for the taking.

A symbol of Texas pride.

This cathedral dedicated to Louis IX, sainted King of France, holds many secrets.

The world-record holder for the longest bridge stretching continuously over water.