The final resting place for the remains of 143 Habsburg royalty.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

A pedestrian island in the middle of world-famous Times Square emits a strange (and purposeful) humming noise.

The most iconic structure in Scotland has been home to bishops, colonels, and Sean Connery characters.

An unusual round church in London with a Templar past.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

Thousands of well-dressed mummies below a monastery.

Famously misunderstood wonder of the ancient world

Macabre astrological automaton clock dating to the late 1400s.

The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

London's last remaining public soapbox site has seen speeches from Karl Marx, Vladmir Lenin, and George Orwell.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

World's second largest particle accelerator, where nature reveals its secrets.

What was once the second largest steel mill in the US is now a sprawling complex of modern ruins.

This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

The twin towers in this Chicago fountain use 50 foot tall video screens to spit on people.

This historic hotel invented the chocolate brownie.

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

A once-magnificent collegiate church is falling into ruin.

Christ's blood preserved in a Belgian town.

Don't be fooled by this fake medieval facade even if it is almost 300 years old.