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

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

This plot of old-growth forest is the largest surviving remnant of New York City's original woodland.

This enormous banquet-themed artwork honors over 1,000 notable women throughout history.

An ancient tunnel in Jerusalem built to redirect water in the event of a siege is one of history’s great architectural innovations.

This daunting 1st century fortress was purportedly the site of one of the most dramatic revolts of the Jewish-Roman wars.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

A "gravitational anomaly" located in the redwood forests just outside of Santa Cruz, California.

The mysterious wonder of an underground waterfall is illuminated by multicolored lights.

The house that Frank Lloyd Wright "(shook) out of his sleeve at will" at the age of 86.

Frank Lloyd Wright's most iconic home dangles over a Pennsylvania waterfall.

A bizarre house filled with an astounding array of collections.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

A rare tour of a commercial jet assembly plant, held inside one of the largest buildings in the world.

I-95's Tijuana-style celebration of kitsch at the Carolina border.

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

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

This float factory takes the mask off of Mardi Gras and lets visitors see where the magic happens.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

Originally a brothel during the Klondike Gold Rush, this bar once used dolls to denote when ladies were working.

A historic freight system that found the true gold rush is in tourism.

A rare chance to get up close and personal with a 13-mile ribbon of ice near downtown Juneau.

An 80-year-old house built out of newspapers.