The Stonehenge of Wales is one of the grandest neolithic dolmens still in existence.

A harem-inspired Moorish fantasy design in a Victorian-era Welsh castle.

A hermit's tiny cell built into the cliffside that saved him in South Pembrokeshire.

A miniature Italianate fantasy village on the coast of Wales and the set of ITC classic "The Prisoner."

This amazing example of Valencian Art Nouveau looks more like a cathedral than a public market.

There are hidden patterns on the subway seats of some Stockholm metro cars.

A statue that stood at the center of a long copyright battle.

The 19th-century home of Count and Countess von Hallwyl is now a museum.

This unique sculpture is often overlooked by pedestrians.

Finally reunited, the three effigies now stand in a museum courtyard.

A king's bloodstained shirt is among the gruesome collection of artifacts displayed below Stockholm's Royal Palace.

When this 18th-century observatory's meridian was moved, it set Sweden's time back by 0.04 seconds.

This grisly exhibit houses skeletons and weapons from a devastating 14th-century clash.

Stockholm's narrowest alley is barely over two feet wide.

The discovery of an old wall led to the creation of this fascinating museum about the city in the Middle Ages.

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.

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

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

The library's graceful rotunda is like a bibliophile's temple.

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

A rare surviving Victorian greenhouse designed specifically to house giant water lilies.

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