In the early 1800s, surgery was also a show.

The origin of this mechanical boy was a mystery until he revealed his maker by writing it in perfect cursive.

Huge masonic hall in Philadelphia with lavishly themed rooms.

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

A rare view of a preserved Victorian science museum.

Where America's first doomsday cult awaited the end of the world.

A layered tribute to the work of mosaicist Isaiah Zagar.

Dug as a secret royal escape route, the tunnel became a wartime bomb shelter and dumping ground for vintage cars.

A whimsical tower with a spiral staircase, inspired by the Space Age and the Möbius strip.

An unrealized dream to wirelessly electrify the entire Earth.

The spectacular collection of one of the world's best woodcarvers.

This tiny museum kept in a B&B laundry room holds the death mask of notorious bank robber Pretty Boy Floyd.

First a root beer ad, then a golf course clubhouse, and finally a massive teapot.

The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

A painfully obvious spy house sits right across the street from the Russian Embassy.

Hidden behind Lincoln's head is a 70-foot-long chamber containing enamel plates documenting American history, sealed in a teakwood box in a titanium vault.

One of New York's best collections of pinball is hidden in a secret bar in the back of this laundromat.

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

A morbid secret lies hidden within the beautiful walls of the Boston Athenaeum.

A room hidden behind a swinging shelf in the children's section.

This Boston medical museum features the skull of the famous medical case of Phineas Gage.

An enormous, inside-out glass globe built in 1935.

Elevated freight railway turned wildly successful urban park.

Try not to get slimed in Tribeca.