This neo-Gothic former auto showroom is one of the few remaining reminders of Brooklyn's "Automobile Row."

Headquarters of the world's fourth largest Hasidic sect and the first of many "770s" around the world.

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

The most confusing clock in New York.

This Fifth Avenue church has long been the favored worshiping place of Broadway actors and vaudeville performers.

Walking around West Harlem reveals a scavenger hunt of beautiful bird murals.

A centuries-old church stands as a testament to Boston's "father of architecture."

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

A Manhattan Episcopal church with an eerie underground crypt.

The oldest surviving synagogue in New York City is now a soaring art space.

Lovers proclaim their unbreakable bond by leaving their names on locks fastened onto the Shoreditch fence in East London.

A cluttered and astounding collection of antiquities and curiosities.

Hear the quietest sound from across the dome.

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

Richard III supposedly disposed of his nephews' bodies here in an effort to seal his claim to the throne.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

The name of this famed hospital was once a byword for the horrors of medical and psychiatric care.

Rat sculptures try to infiltrate the Graybar Building in an architectural tribute to New York City's nautical history.

Whether you're up or down, the Elevator Museum is worth a stop.

A small peaceful park and waterfall tucked amid the urban grind of Midtown Manhattan.

A celebration of capitalism in Midtown.

The graveyard holds the remains of Irish immigrants who arrived in Queens after fleeing the Great Famine.

New York City's only wildlife rehabilitation center treats more than 3,000 feathered and furry patients each year.

A replica of a 7th-century church hides in plain sight in the middle of the concrete jungle.