Europe's largest prehistoric mound – burial site of a legendary king?

It's possible to walk inside one of the largest Neolithic tombs in Britain.

The largest stone circle in the world has ended up bringing up more questions than it has answered.

Among Europe’s most spectacular Ice Age painted caves still accessible today.

Ancient paintings known as the "Sistine Chapel of Cave Art."

Amsterdam's former hotspot for public executions and dissections.

A beautifully eclectic mix of architectural styles.

The attic of a four-century-old canal house hides a clandestine church.

This gorgeous reading room houses the oldest and largest art history library in the Netherlands.

A beautiful footbridge with over 2,000 glass sculptures along the walls and ceiling.

Designed by Buckminster Fuller, this relic of the 67 Expo survived fire and ice.

This replica of the Greek structure is in the heart of Nashville.

Legend tells how a Spanish soldier disappeared from this isolated sentry box without a trace.

This bleach-white graveyard overlooking the ocean is accessed through a tunnel.

Showing films since the silent era of the 1920s, it is now the last movie house in downtown Newport.

This small museum is home to cannons cast by Paul Revere and the last remaining uniform of Egyptian President Anwar Sadat.

An unexpected Easter egg lurks in the background of a cherub wall relief at the Breakers mansion.

Three and a half miles of cliffs, rocky beaches, Gilded Age mansions and 40 Steps to nowhere in particular.

Rhode Island's tallest building bears a resemblance to the "Daily Planet" building and has been empty for more than five years.

Home of Philip Johnson, one of the 20th century's most influential architects.

These wire animal sculptures commemorate the exotic inhabitants that once called the Tower of London home.

All unmarked mute swans on the Thames are owned by the Queen per a tradition that began in the 12th century.

A beer pipeline runs beneath Bruges.

A floating cat sanctuary on an Amsterdam canal.