A miniature rainforest is growing inside of a Midtown Manhattan office building.

In the St. Francois Mountains in the Ozarks at 1,772 feet above sea level, Taum Sauk Mountain is the highest (and possibly oldest) peak in Missouri.

An abandoned concrete jungle surrounded by a lush park.

An abandoned observatory in the middle of the Illinois prairie.

Tucked away in the forests of Indiana resides an abandoned waterslide that is now a popular graffiti haunt.

A once-booming Mississippi River town with a history of racial violence is now eerie and mostly abandoned.

An iconic location along the Los Angeles River where countless movie scenes are filmed.

Hidden above a drug store on a nondescript corner of Lincoln Heights is a private clubhouse for intrepid explorers.

This gaping hole in the middle of a remote mountain lake looks like a portal to another dimension.

This is what trains will look like after the zombie apocalypse.

Try not to get slimed in Tribeca.

One of the world's longest murals depicts the history of diversity in Los Angeles.

An extravagant western hotel where every floor is the "ground floor."

Hollywood's most famous landmark, the "temporary" sign that has stood for decades longer than intended.

This stockpile of junked electronic and mechanical gadgets is a favorite among Hollywood prop masters.

The first park built over a freeway is a brutalist masterwork.

A wall of chewing gum moonlights as collective art.

This supper-club-turned-concert-venue still serves drinks at its original rotating bar.

One of several Lilliputian portals that are ready to transport passengers to other dimensions, if they can find them.

Visitors flock to see this church tower's unintended feature: It happens to resemble a giant chicken from multiple points of view.