Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

Once home to seven different roller coasters, Glen Echo has undergone many transformations since its founding in 1891.

Tiny observatory made big contributions to the study of the Earth's motion.

This enormous Hindu temple in Queens serves incredible dosas in its basement canteen.

Order scoops of pandan, lychee, and black sesame at this family-run institution.

Dodge prohibitionists and slide through the telephone booth in Crif Dogs.

A tiny museum housed in a New York freight elevator specializes in the "overlooked, dismissed, or ignored."

A treasure trove of artifacts, books, and artwork from the "golden age" of exploration.

Amid the bustle and noise of the Financial District hides a secluded garden oasis above the city streets.

A terrific purveyor of natural history objects and curios.

Also known as the Founding Church of Scientology.

A small token of gratitude from freezing cold journalists who were given a warm haven while covering JFK's inauguration.

This unique museum cafeteria showcases the history and regional diversity of African American cuisine.

Washington's top-secret Cold War-era doomsday communications tower is located in a small neighborhood park.

An obscure public service from the U.S. government that redeems burnt, moldy, and soiled old greenbacks.

The most decorated dog of World War I is preserved in the Smithsonian.

An Industrial Revolution-era public work that purified water using nothing but sand.

A computer bug so primitive it was an actual insect.

The remains of Martha, the last known passenger pigeon, serve as a tool to educate about conservation.