This subterranean oyster house has been the pearl of Grand Central Station since 1913.

This giant wooden treehouse within a sprawling garden has its own eatery.

The oldest library in Scotland was built from the remains of a church to hold a churchman's library.

The first geometric self-supporting spiral stairs in Britain are a truly beautiful sight.

Near Belgrade, an ancient-looking sarcophagus serves as a World War I monument.

A grave marker depicting a body snatching tableau on a 19th-century tombstone.

A striking glass tribute to two sisters who suffered during Scotland's "Killing Time."

A free public golf course hides in plain sight in the heart of Scotland’s capital.

A serene public space nestled within the remains of Glasgow’s Victorian maternity hospital

Glasgow's memorial to the International Brigade volunteers from Great Britain who fought and died in the Spanish Civil War.

The best-preserved ancient theater in the world.

A maze of underground tunnels beneath one of the most beautiful forts in Serbia.

This unique rock formation is quite the local celebrity, although one day it may come crashing down.

This once-controversial and slightly confusing statue of Achilles was built out of captured cannons.

The abandoned transportation hub hides within the Glasgow attraction it once served.

Alexander Hamilton’s creation caused quite a bit of controversy.

It houses a menagerie of wondrous taxidermy specimens from around the world, including the remains of a famous gorilla.

A mysterious ruin shrouded in more folklore than fact.

Learn local history while picking up groceries at this museum tucked inside a supermarket.

A 16th-century castle unexpectedly nestled within a post-war housing development.

A familiar otherworldly creature guards this 12th-century Scottish abbey.

This slice of 1960s Danish modernism does not conform to the Oxford college stereotypes.

Sprawled across the Great Hall ceiling are various constellations and images relating to the zodiac.

This modern, multimedia museum takes visitors on an evolutionary journey back in time.