This natural marble cave is one of only five national monuments in Oregon.

See massive fossils that are over 200 million years old in northeastern Arizona.

A sharp bend in a dramatic river canyon cut through red rocks.

Most-visited and most-photographed slot canyon in the American Southwest.

The first American department store, and home to the largest operating musical instrument in the world.

This Philly cemetery is the eternal home of many famous area residents, including Rocky Balboa's wife.

The body of St. John Neumann and his collection of hundreds of relics, on display in a Philly church.

Tour the dark and beloved poet's former cobwebbed basement, which may have inspired "The Black Cat."

Philadelphia boasts one of the best — and most often overlooked — traditional Japanese gardens in North America.

The world’s first penitentiary, meant to be humane, drove men insane.

This elaborate towering structure was once famed for its revolutionary height.

A layered tribute to the work of mosaicist Isaiah Zagar.

A huge musical instrument played by the ocean.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

This shop specializes in oddities and Victorian-inspired wonders.

A historic hotel that made a cameo in Hitchcock's classic film has no intention of letting guests forget its fame.

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

A tiny theater hidden in an alley plays a constant stream of short silent films for anyone willing to peer through the peephole.

Since 1973, this block has been home to the most concentrated collection of murals in San Francisco.

This ultra-modern California span is actually a titanic solar clock in disguise built by famed architect Santiago Calatrava.

This graffiti-covered bridge is the quintessential vision of a place for disillusioned youth to escape the complexities of burgeoning adulthood.

A collection of 20th-century automata, penny arcade games, and musical contraptions.

A psychedelic labyrinth on the San Francisco bay.

A playground built by the kids that is a child's wonderland, and a helicopter parent's nightmare.