The perfectly preserved underground rooms where Churchill plotted the war against Germany.

This statue and park honor the Swedish chemist Jacob Berzelius, one of the founders of modern chemistry.

The Swedish flag over this small naval fort signals that the nation is at peace.

It is said that each of the white stones in the red facade of this medieval house represents the head of a murdered Swedish noble.

Sweden's "good old days" painstakingly re-created in a model village.

Stockholm's deepest subway station is also a stunning ecological wonder.

It houses the remains of a 17th-century version of the Titanic.

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

Dublin's most modern, visually spectacular bridge is modeled after Ireland's national emblem.

A particularly disconcerting tribute to Irish martyrs.

One of Ireland's most infamous prisons for rebels including men, women and children.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

A man's head is enshrined beneath a statue near the first building constructed for the modern Olympic Games.

Heralded as the world's first theater, these ruins are often overlooked as they reside in the shadows of the Acropolis.

An ancient octagonal weather station named for the eight Greek gods of wind.

The hallucinogenic center of the ancient world.

This noble mash-up in eastern Luxembourg is part Medieval, part Renaissance, all castle.

This statue once earned the distinction as one of the "Three Major Disappointments of the World."

The most playful of the life-sized statues that make up Singapore's "People of the River."

The largest pool at its elevation sits on top of one of the most expensive resorts in the world.

Singapore's landscaping project is home to 18 incredible Supertrees.

Holy Hindu shrine in an enormous, monkey-filled limestone cavern.

This enormous monument is one of the most iconic structures in Tokyo, rudely nicknamed "The Golden Turd."

Once a black market electronics marketplace, now an otaku shopper's paradise.