The highest point in New Jersey is marked by a massive, if simply named, obelisk.

A 19th century hat factory still stands as a crumbling ruin in upstate New York.

This abandoned factory on the Hudson River once churned out a million bricks a week.

A grand Gothic Revival basilica with stained glass depictions of Montreal's religious history has only one soul resting in its crypt.

Its columns were all carved from the same white oak tree.

Controversial tribute to the heavyweight champion boxer who grew up in Detroit.

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

The Old Courthouse takes visitors on a captivating trip through St. Louis' timeline.

This equestrian statue of Constantine the Great has been the subject of criticism for centuries.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

The ruins of the largest gladiatorial school in Rome are largely hidden under modern streets.

First founded in 1472, this is the oldest bank in the world. Its history may explain why we call financial institutions "banks."

These medieval skyscrapers dominate the skyline of this small Tuscan town.

The only visible reminders of an elaborate engineering project that kept the tower from reaching the tipping point.

A copy of the famous statue can be found in this Florence piazza, along with one of the most breathtaking views of the city below.

Two stone columns flank the grand Venice square, but there were supposed to be three.

This palatial spiral staircase was so unusual the name "snail" was given to the noble family who built it.

Where Venice's gondolas go for a tune-up.

Erotic art covers the walls of the largest ancient pleasure palace.

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

The walls and streets of the ancient city are peppered with penises.

Ancient snack bar of the Roman Empire re-opened.

A mysterious echo seems to defy the laws of acoustics.