A beautiful deserted greenhouse in the middle of a park.

The smaller of the three towers of San Marino is a former prison inaccessible from the ground level.

High in the clouds of San Marino sits an ancient tower with some curious prisoner graffiti.

The only urban monument in the world designed by the great surrealist painter Salvador Dalí.

This semi-hidden Manhattan restaurant is based out of a loading dock.

Tucked away amidst some of the most famous addresses in the world is New York’s only fraction of a street.

Hidden in Central Park's Ramble is a troublesome cave buried just beneath the surface.

An unassuming secret door once led to a legendary watering hole.

Red frames showcase remnants of one of New York's original subway stations.

This monument to a veteran of the Mexican-American War is one of only two in Manhattan that serve as an actual mausoleum.

A 19th-century politician who died after walking home in a blizzard is honored with this Manhattan statue.

A monument celebrating the idea of reaching inaccessible places.

Electrical pylon in the shape of Disney's beloved mouse.

This Bogotá museum houses the world's largest collection of pre-Columbian gold relics.

This tiny shop has been serving traditional tamales for more than 200 years.

Cathedral carved out of salt, located a mile below the Earth's surface.

This futuristic bridge is one of the longest self-anchored pedestrian bridges in the world.

A sculpture of the famous photograph stands on San Diego's "Greatest Generation Walk."

Lucha Libre (Mexican Wrestling) themed taco shop.

One of the few remaining carousels built by master amusement park carver Charles I.D. Looff.

San Diego's most historic and haunted home.

An extraordinarily ornate museum in San Diego holds wondrous anthropological treasures.

Behind this beachfront shop lies a spectacular, colorful sea cave with an equally colorful past.

An inconspicuous footbridge beloved by San Diego locals.