Legend says this sacred tree was a gift from goddess Athena.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

A trompe-l'oeil statue honoring the first guide dog in North America.

Originally built in 1869, this castle is currently part of Felician University's campus.

Carved fountains poignantly placed in parks and in front of special monuments.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

This multisensory alley has the ability to remind bustling citygoers to stop and smell the roses.

A unique tribute to the millions of animals who served and died for the British military.

A floating cat sanctuary on an Amsterdam canal.

This historic Amsterdam bar used to accept sailor's monkeys as payment.

Famed for its pie, this eatery has a hidden tunnel that allowed Catholics to secretly walk to church during the Reformation.

Copenhagen's celebrated theme park and gardens.

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

Once a meeting point for great thinkers, and the midpoint of the country.

This ordinary street was made infamous by a legendary visit from the devil.

Beneath Denmark's Højbro bridge, a bronze merman and his seven sons forever mourn for the mother and wife who left them for land.

This bridge's unique architecture honors nautical heritage and encourages self-awareness.

Danish tourist destination well known for open stalls where vendors sell marijuana on the street.

An enormous playhouse designed to look like 21 stacked Lego bricks, with another 25 million colorful Legos inside.

This beautiful deer park was built so King Charles I and his court could go hunting while escaping a deadly plague outbreak.

England's oldest surviving hedge maze has been confusing visitors for over 300 years.

The world's largest grapevine has produced a delicious harvest at Hampton Court Palace for almost 250 years.

In 2013, historians discovered a hidden room devoted to the art of making royals' hot chocolate.

Chelsea's soldiers were given strict orders when crossing this historic bridge.