A museum dedicated to a secret military hospital hidden beneath a castle in Budapest.

A 19th century artistocrat's mansion, turned into a library, hidden in a modern library.

Sleepy fishing port not included on many maps.

Crumbling necropolis set high above Fez.

Along the most northwestern point in Africa is an ancient cave surrounded by legends.

Founded as a refugee camp, now a popular tourist spot.

The ruins of a monumental tower in the heart of Lebanese mountains still puzzle archeologists.

This restaurant combines two Finnish traditions in one place: warm-weather relaxation and outdoor carpet-cleaning.

Every summer, an open-air swimming pool appears at the base of a Finnish city's beloved winter attraction.

More than 200 eclectic sculptures surround the artist's home.

The church's remarkable frescoes incorporate Finnish artist Hugh Simberg's trademark themes of death and the supernatural.

The tiny, studious rodents greet visitors to the National Archives of Finland.

A little-known sculpture park of contemporary environmental art in a Lapland forest.

This mesmerizing, colorful structure looks like a tent made from stained glass.

Within the Saudi Arabian desert lies a 2,000-year-old ghost town made of stone and mud.

Honoring one of the first boats to leave Ulster destined for America.

The artwork is a community's ode to the "father of Irish tourism."

Local legend says there's treasure hidden within its crowded graveyard.

This picturesque lighthouse at the edge of the Irish Sea looks like a giant stone pencil.

A giant sculpture of the legendary "Salmon of Knowledge" celebrates the return of fish to Belfast's River Lagan.

For part of the year, this innovative greenhouse is painted white to keep the plants from getting scorched.

The ship built to ferry passengers and goods to the doomed Titanic is now the last remaining White Star Line vessel.

A museum marks and documents the site of the Titanic's launch.

The ruins of this medieval castle in Northern Ireland have inspired artists from C.S. Lewis to Led Zeppelin.