A winding path built in secret on the edge of the continent.

A walk-in working camera obscura produces 360-degree live images of the San Francisco coast.

A crumbling hospital from the 1850s on Roosevelt Island.

The United States Capitol's former columns still stand.

This landmark cemetery in Boston was created more than 300 years ago.

Golden Gate Park's historic collection of plants.

Northern Ireland's Brobdingnagian stepping stones.

Quite simply the largest tree in the world (by volume).

Carnivorous plants, medieval aphrodisiacs, and the largest original wood structure glass conservatory in the western hemisphere.

A church of bones, decorated with 40,000 human skeletons.

I-95's Tijuana-style celebration of kitsch at the Carolina border.

A layered tribute to the work of mosaicist Isaiah Zagar.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

A huge musical instrument played by the ocean.

The deepest lake in the United States, and once the site of epic destruction that lives on in legends.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

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

This Dutch-styled residential building was originally a cocoa company's World's Fair showpiece.

The thousands of shades on display — some toxic, others impossibly rare — are a library of more than just color.