The world's first invisible city square is an homage to a man who pushed the boundaries of art.

An overlooked marble is the only surviving in-place 18th century example of the measurement that changed how we define distance.

A New Hampshire grave with a grudge.

The tallest city hall in the world offers an excellent bento box.

Designed as a labyrinth, this subterranean prison was crafted without bars or doors.

Shipwrecks, ruins, and turtles are all that remain on this haunting Caribbean ghost island.

A giant Troll lurks under one of Seattle's oldest bridges.

In northeastern Poland, the ruins of a massive granary overlook the Narew River.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

This giant monument of the RCA mascot is a beloved fixture in Albany, New York.

A CT scan revealed the identity of this 3,000-year-old mummy that everyone erroneously thought was female.

An out-of-place grove of sequoias thrives in northern Spain.

A shiny sculpture celebrating the mighty mollusk.

Local legend says Isaac Newton built this footbridge without any screws, bolts, or nails.

The largest and best-preserved Roman amphitheater in Africa was designed to seat 35,000 people.

The strip club's VIP lounge is actually a rare repurposed Futuro House.

A tiny, unassuming park in Tampa that belongs to the Republic of Cuba.

Step back into the glory days of Florida's nascent tourism industry at this Gilded Age palace.

Three bridges and one giant canyon make up this fantastic Spanish settlement.

A memorial to the beloved brown bear that served in the Polish army during World War II.

Great Britain's only hat-making museum.

This historic funicular system combines the old with the new while offering delightful views over the surrounding valley.

This geometric feat is a testament to the Incas' mesmerizing architectural abilities.

The inspiration for H.P. Lovecraft's horror stories and Batman's Arkham Asylum is now a condominium complex.