The world's longest known cave system.

Left untouched since a double murder-suicide in the 1960s, Los Feliz murder mansion remains a neighborhood mystery.

Read a book next to a Midtown waterfall.

The United States Capitol's former columns still stand.

Detroit’s Eastern Market has been transformed into an outdoor museum with colorful murals that address social issues and symbolize the city.

"The Most Boring Road in the State."

The concrete shell of an industry giant remains as a playground for graffiti artists, auto scrappers, and paintball warriors.

The world’s largest Masonic temple was saved by the White Stripes.

A bizarre roadside attraction and the first instance of miniature golf in the world.

This hidden sculpture garden full of Wild West art is one of San Antonio's best-kept secrets.

These boots are made for selfies.

This small museum gives visitors a chance to soak up the history of the "sponge capital of the world."

An artsy hidden staircase leads to breathtaking views of San Francisco.

A peculiar mansion built by the troubled heir to the Winchester Rifle Company fortune.

Over a thousand feet beneath the Detroit streets is a subterranean metropolis few are allowed to enter.

The writing studio of an American adventure author, built in the style of a medieval castle.

The only surviving prototype for Buckminster Fuller's house of the future.

The birthplace of the Ford Model T is now a museum full of antique cars.

Standing guard on top of an old, vacant ice cream shop.

A painted-over wall in Detroit originally built to segregate a black community from an adjacent white development.

A wacky two-story folk-art assemblage of carved and found objects, with lights, motion, and sound now in need of financial support.

The bones of an old zoo crumbling in the shadow of a new one.

There aren't too many operational funiculars around, but Pittsburgh has two!

The only way to see Pittsburgh is from the top of this lookout point, just like the ancient members of the native peoples did.