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

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

Dine on food tied to Viking history and legend at this subterranean Stockholm spot.

An illuminated manuscript comprising the life's work of a lone monk, inexplicably decorated with a portrait of Satan himself.

The grand complex of buildings that comprise Liverpool's Exchange Flags includes a vast World War II bunker that has been frozen in time.

This stone once marked the boundaries of Liverpool's medieval markets.

Charles Dickens described the concert room in this amazing Victorian hall as "the most perfect room in the world."

Pyramid shaped monument with a tall tale attached.

17th century puritan church with connections to the Salem Witch Trials.

A rocky outcrop where monks hid their most holy relic while escaping Danish invaders.

The medieval-looking hammer beam teak roof may be a Victorian vanity, but it's still absolutely magnificent.

These upturned herring boats make nifty storage sheds for fishing goods.

This restaurant's specialty is "a major enigma for food historians."

With lush plants and flowers, huge trees, ponds, and hidden monuments, this place feels a bit like discovering Narnia.

The U.K.'s first underground railway line is now a lively thoroughfare for runners and cyclists.

Remnants of the 16th-century defensive wall still stand unassumingly within Edinburgh.

These steps offer a breathtaking view of one of Europe's most besieged fortresses.

This king penguin is a knighted brigadier of the Norwegian Army.

Now home to a drinking establishment, this building has a macabre history.

This small museum in a 17th-century building honors three iconic Scottish writers.

A library where thousands of books explain how to avoid another Great Recession.

A labyrinthine network of chambers with a storied past hides below Edinburgh's South Bridge.

An American ghost town hides along a side street in Scotland's capital.

This allegedly haunted 16th-century tower house-turned-museum exhibits thousands of spectacular objects.