A Norwegian-born sculptor created these soaring guardian angels at the entrance to Hoover Dam.

An old railroad grade built for the construction of Hoover Dam is now a recreational trail featuring several tunnels and sweeping views of Lake Mead.

Dyed by iron oxide over centuries, these sandstone rocks rise thousands of feet into the sky.

Brightly colored 30-foot-tall totems light up the desert sky just outside Las Vegas.

The oldest living tree in Manhattan comes shrouded in sinister legend.

An aptly-named street near the birthplace of the modern LGBT rights movement.

Hidden behind a gate in Greenwich Village is a little farmhouse that once served as the writing studio of a bestselling author.

Nope, not Washington Irving's house.

A touching tribute to the "Queen of Soul."

Once a ferry dock, radio transmitter, and now a new Greenpoint park.

Two large-scale sculptures of Adam and Eve greet visitors in the nude at the Time Warner Center in NYC.

This abandoned factory on the Hudson River once churned out a million bricks a week.

The remains of what was once the world's steepest passenger funicular.

A 19th century hat factory still stands as a crumbling ruin in upstate New York.

The oldest continuously inhabited street in America.

This old cement mine has been used as everything from a mushroom farm to a recording studio.

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.

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

Sniff the Titan Arum's rotting flesh.

Heralded as the world's first theater, these ruins are often overlooked as they reside in the shadows of the Acropolis.

New York City's only radical feminist independent bookstore.

Become a prohibition rebel.

A hands-off space for graffiti artists to hone and display their skills.

The pockmarks across the building's facade are remnants of the Blitz.