Op-art architecture designed for happiness.

The former private quarters and office of Dr. Sigmund Freud now hosts a museum housing the works of the founding father of psychoanalysis.

The topiary maze at the Habsburg hunting lodge.

This one-time health resort was used by aristocrats around the world.

A whimsical bridge adorned with decorative dragons.

This abandoned Slovenian military barracks has become a punky-political art squat.

Stand at the center of this lakefront sundial, and you'll become part of the timepiece.

A Nesting Doll of Churches.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

A merchant court dedicated to the fictitious King Arthur is heavily adorned with bizarre Renaissance art.

St. Mary's features one of the most spectacularly decorated cathedral interiors in all of Europe.

The oldest housing complex in Riga is a mini timeline of architectural trends.

A black cat protests the City Guild in Riga's Old Town.

Latvia's symbolic mountain-shaped national library is home to millions of cultural tomes.

This medieval Estonian tower provides access to a series of tunnels that have been home to soldiers, punks, and fine art.

The Guardian of Tallinn.

A church filled with the bones of hundreds of virgins martyrs—or so they say.

This network of conjoined cellars was riddled with traps and supposedly allowed the townspeople to pretend their homes were deserted.

A rare tour of an aristocrat's private home reveals valuable 17th-century paintings from artists like Rembrandt.

A public urinal so pretty, it was declared a national monument.

Thanks to both terrific preservation and historic vandalism this ancient site is known as the "Heart of Neolithic Orkney."

This tin chapel was built by POW's during World War II and is painted to look like something much more grand.

Enter the world under the hill at this ancient UK burial chamber.

Possibly the oldest of Britain's ancient henges is also one of its most stark.