The site of the deadly Triangle Shirtwaist Factory Fire.

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

The most confusing clock in New York.

The only subway station in the city that still makes use of gap fillers.

Hidden in one of New York's oldest subway stations is the final remnant of the site of the bizarre Shakespeare Riots.

Touching mementoes from those who didn't make it back from World War I still hang in one of New York's oldest bars.

Salute the leader of the proletariat.

One of the few remaining American elm trees in New York’s Tompkins Square Park was the birthplace of a new religion.

This simple Manhattan salt house is artfully shaped... well, like a giant granule of salt.

Try not to get slimed in Tribeca.

A touching tribute to the "Queen of Soul."

This abandoned ironworks was once the most important military supplier in America.

Now a retreat center for the faithful, it once provided training for clergy—but it began as a farm owned by a famed financier and his opera singer wife, who built a surprise in the backyard.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

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

A remnant of the original World Trade Center complex continues to serve as a commuter gateway.

Pulled from the rubble of one of the worst modern tragedies, a steel crossbeam became a symbol of hope for New Yorkers.

The last living thing to come out of the rubble after 9/11 is now a symbol of hope and resilience.

This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

This cemetery has graves dating back to the 17th century, including the city's oldest carved tombstone and an ominous cryptogram.

Unrepaired walls from a 1920 anarchist bomb attack.

Possible relics of the ancient Roman city are hidden in this restaurant's façade.

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

Under a glass sidewalk lie the remains of some of Manhattan's oldest buildings.