When the rain falls, this drain system turns into a musical instrument.

The deepest underground city in Turkey was designed to protect 20,000 people behind massive stone doors.

One of only two sites in the United States containing the remains of Buddha.

The now-abandoned tunnels were built for the transcontinental railroad on the route where the first wagon train entered California.

The first blast furnace in the United States that used coal and coke fuel instead of charcoal to make pig iron.

A common entry point to the Griffith Observatory trail holds its own wonders.

A bookstore with an entire room dedicated to damaged and forlorn comic books.

Visit a replica of the estate where Aaron Burr allegedly plotted a treasonous scheme against the United States.

This former fire tower is now a rustic observatory that offers amazing views of eagles, hawks, and the Appalachian Mountains.

This Colorado fire station has been in continuous operation for more than a century.

You can find America's highest suspension footbridge at Grandfather Mountain in North Carolina.

Amid the bustle and noise of the Financial District hides a secluded garden oasis above the city streets.

These molds for fiberglass statues have formed an eerie, accidental sculpture park.

This nondescript tunnel has been featured in a number of iconic movies, from “Roger Rabbit” to “Back to the Future.”

Catch a ride through the Pennsylvania countryside on this historic narrow-gauge railroad.

A bizarre house filled with an astounding array of collections.

This fast-food outlet is the only space and UFO-themed McDonalds in the world.

An ancient cave system in Tennessee’s Appalachian foothills converted to a 1,200-person music venue.

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

Mural made of 100,000 pieces of hand blown glass, and until recently, the largest glass mural in the US.

The longest navigable underground river in the United States is home to countless blind and albino animals.

A fire lookout atop a glacial pinnacle is reached by climbing three vertiginous flights of stairs.

In the mountains of West Virginia is this perfectly preserved Art Deco train station.

The oldest covered railroad bridge still standing in the United States.