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

The New York hotel where tragic visionary Nikola Tesla spent his final hours, destitute and alone but for the pigeons.

A bit of retro transportation flair preserved in the world's largest department store.

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

Lie in a hammock where George Washington stood.

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

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

The "Seinfeld" diner.

Once the tallest building in the world and the site of "the highest dinner ever held in New York" this building now holds the most expensive penthouse in the city.

Wall Street has a new heroine, a bronze statue of a small but fierce girl.

A three-story copper skybridge connects two Manhattan buildings with Art Deco luxury.

One of only two commuter aerial tramways in the United States.

A pedestrian island in the middle of world-famous Times Square emits a strange (and purposeful) humming noise.

The oldest surviving bridge in New York City, which reopened to pedestrians in 2015.

Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

This lower Manhattan bar is set up in an old bank vault that rests beneath a skyscraper that hides even more historic splendor.

Elevated freight railway turned wildly successful urban park.

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

A walk through the historic city center, under the streets of Seattle.

One man's swirling six-acre monument of stone.

A man-made island in scenic San Francisco Bay.

The remnants of two World's Fairs are here, complete with a 12-story globe, a mini-Manhattan, and a UFO-shaped pavilion.

The crown jewel of the Queens Museum is a nearly 10,000-square-foot architectural model of the city originally built for the 1964 World's Fair.

A once crucial portion of the Long Island railroad still lays abandoned, waiting to be turned into an urban park.