This 11th century tower is said to be the oldest building in Oxford.

The beams of the New College, Oxford dining hall come with an amazing story.

A theatre built to house the rowdy Oxford graduation ceremonies became the stage for a debate about God's existence.

Hidden in plain sight, this creepy sculpture watches from above.

Home to the most complete dodo remains known - one head, and one foot.

Ancient Egyptian wigs, South American feather headdresses, a bounty of anthropological artifacts in Oxford.

One of Europe's oldest libraries.

Museum on earth sciences featuring a recreation of a famous curiosity cabinet.

The old observatory in Copenhagen has a spiral corridor used as a racetrack.

This gnarled old tree supposedly sprouted from seeds kept in the pocket of a 16th-century Spanish sailor.

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

This short bridge is the only thing connecting a tiny Irish island to the mainland.

Northern Ireland's Brobdingnagian stepping stones.

These barriers stand as stark reminders of Northern Ireland's troubled past.

An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

Single runway interrupted by a busy road that cuts across its middle.

Sofia's legislative center is continuously reinventing itself.

A gigantic statue of a Russian soldier watches over the ancient city of Plovdiv, a prominent reminder of the Soviet period in Bulgaria.

A vast Communist-era exhibition space in the Bulgarian capital.

"Holy Wisdom" overlooks the city that became its namesake.

This ancient theater, restored in the 20th century, lives on as a venue for dramatic and musical performances.

A collection of art from Bulgaria's time as a communist state.

A striking symbol of the Bulgarian capital.

A Bulgarian monument to Russia's role in World War II is constantly being painted in pop culture protest.