New York's oldest and possibly grandest keeper of books.

Visit the monolithic tomb of America's most famous general.

During the holidays, a vintage subway train whisks New Yorkers back in time.

Everyone from Mark Twain to Teddy Roosevelt has a pipe hanging from the walls of this historic chophouse.

An artist's cute bronze subway sculptures belie his violent artistic past.

Spinning silently in the lobby of an Art Deco masterwork is a massive vintage model of the Earth.

A Manhattan courthouse hides a small but scathing memorial to Holocaust injustice.

New York City's only preserved family home from the 19th century.

Cryptic messages embedded in the New York City sidewalk.

Bowl in splendor, if you're lucky.

Manhattan's lighthouse, erected at the insistence of the unsinkable Molly Brown.

Reverend Jen's unique museum/living room showcases her troll collection.

This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

Deep under Manhattan is the largest construction project in city history. So far, the project has taken the lives of 23 workers, or "a man a mile."

The beautiful tunnel that ran from the lobby to Penn Station is still hidden underneath 34th Street.

Plot your trip through the city on the sidewalk.

This Wall Street bar was once a hub of revolutionary activity where Washington famously bid farewell to his troops.

The "Seinfeld" diner.

A dark, dank room in subterranean Manhattan was the site of a ghastly murder.

A living archive of urban activism and space reclaimed.

Blighted Irish field and the ruins of a 19th-century cottage on the edge of urban Manhattan.

A hidden "place of interment for gentlemen."

A clock set into the concrete outside a Manhattan jeweler has been telling time underfoot for over a century.

An uber-secure, windowless tower of doom in the center of Manhattan is an NSA spyscraper.