A commemorative plaque hides a door that leads down to the New York Public Library's underground book bunker.

The New York hotel where tragic visionary Nikola Tesla spent his final hours, destitute and alone but for the pigeons.

A series of fish plaques that are embedded in the malls of Ocean Parkway.

A mosaic made of materials gathered from this Brooklyn community adorns the walls of this tunnel.

Two monstrous warehouses. One now holds priceless works of art, the other stands abandoned and dilapidated.

These century-old townhouses contain some of the first car garages built in the United States.

In Little Caribbean, an ice-cream shop serves up regional flavors, including soursop, Irish moss, and "greatnut."

A miniature version of a legendary Dutch boulder.

This statue is in the center of San Jacinto Plaza, commemorating the live alligator pond that once stood in the area.

A historic 1929 art-house cinema that features independent, classic, cult, and foreign films in an atmospheric setting.

For 14 years, this former stray dog greeted every train passenger that arrived in Fort Collins.

Built in 1981 in collaboration with Andy Warhol, this giant piece of pop art stands on the campus of Colorado State University.

Great place to have a drink and a bite to eat in an atmosphere laden with New York's Bohemian past.

This installation turns abstract economics into a stark, public spectacle.

An homage to Jackie Gleason's bus-driving character from 'The Honeymooners.'

Captain America, Sub-Mariner, and the Human Torch were all born in this art deco Manhattan masterpiece.

Manhattan's Thirteenth Avenue was made on landfill then deliberately destroyed — apart from one small, obscure block.

Fake subway tiles were installed to cover a design that resembled the Confederate flag—it's unclear if the resemblance was intentional.

What was once a vast naval cemetery is now home to nesting birds and pollinating bees.

Beloved bar home to musicians of all eras and reputations.

A lone traffic cone perched on a ledge has remained unmoved since at least 2011, unofficially earning the status of a tiny Chicago landmark.

A hot dog stand where the heads are just as hot as the dogs.

The 30,000-volume library is one of the world's most impressive poetry collections.

Small and slightly hidden, the American Writers Museum is preserving the legacy of America's finest authors.