This Irish show cave is said to have been the site of a Viking massacre that claimed 1,000 lives.

An 80-year-old plane tree is devouring an iron bench at Ireland's oldest law school.

The enchanting archway is the only surviving portal into Dublin's lost medieval wall.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

A domino effect created with Britain’s iconic telephone boxes.

A kaleidoscopic warehouse-maze of handmade neon signs.

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.

An iconic red telephone box turned tiny art gallery.

This former train tunnel is filled with lines from a poem crafted by Robert Louis Stevenson.

The world’s first museum dedicated to the history of childhood opened in Edinburgh in 1955.

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

Every birth, death, and marriage is recorded in these color-coded leather-bound books.

17th century streets hidden under Edinburgh were once a breeding ground for the black death.

In France, a medieval-style home pays homage to an intrepid explorer who discovered Québec.

Hundreds of hidden passageways weave through the old quarters of Lyon.

The Swiss artist's bulbous and overgrown shape-shifting sculpture controversially graces the center of Bern.

A trough of 700 strange bronze faces runs through a narrow alley in Ljubljana's old town.

The holes in this wall provide a glimpse into Jewish life in Budapest, both past and present.

The metal leaves on this tree are engraved with the names of Holocaust victims.

Budapest's Communist-era statues, banished to the suburbs.

Once the home of a hermetic monk, this cave now houses a small church.

A series of caves under Castle Hill that once held the prisoner Vlad Tepes, better known as Count Dracula.

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

This Budapest bar allows drinkers to leave their mark on the walls, floor, and even ceiling.