Climb this overlooked gem's spiral staircase and you'll be rewarded with spectacular views of Glasgow.

A scattered trail of street art adds a pop of color to the city's stark structures.

"Respectful to the dead, safe and sanitary to the living, dedicated to the Genius of Memory..."

Climb a steep hill in 90 seconds on the second-oldest urban subway in the world.

The most metal church of all time was built in record time because of an international, pious pissing contest.

This museum was invented in a novel before being made real by the author.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

Five sultans and their families rest in eternal splendor, teeming with overlooked beauty and drama.

A marvel of Byzantine engineering under the streets of Istanbul.

One of the world's heaviest musical instruments towers within a popular urban park.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

The most visited, and possibly most controversial, museum in Germany.

A whimsical and twisted animatronic monster tour beneath the streets of Berlin.

During World War II, this rice mill became a Nazi concentration camp.

The summer residence of a Spanish ambassador who brought viticulture to an impoverished region, sparking its transformation into one of the world's best wine regions.

A star-shaped fortress town fort built in the geometric model of the Renaissance utopian city.

An ancient rogue artist community hidden next to one of the world's most glitzy and glamorous cities.

Inside this McDonald's you can dine on your Big Mac and fries next to a 2,500-year-old Roman wall.

A fairy tale castle in modern Rome.

2300-year-old Roman road connecting the empire.

The underground sanctuary of a mysterious ancient cult.

A stunning medieval castle houses this eclectic, interactive tribute to all things wine.

The mountaintop inspiration for Umberto Eco's "The Name of the Rose."

A massive mausoleum towers over the gravestones in a 19th-century Italian "model village."