Live data is transmitted from the Atlantic coast to instantly recreate the ocean waves in this fountain at the NOAA headquarters.

It appears as if a man is standing behind this giant airport clock, painting the hands in real time.

An abandoned early-20th-century boomtown sits within the Calico Rock city limits.

This natural Icelandic fissure allows divers to swim right between two volatile tectonic plates.

At Washington's Dulles Airport is a satellite museum (no pun intended) with three quarters of a million square feet of aircraft history.

The semi-reclaimed ruins of this canal were once part of an ambitious plan to reroute the mighty potomac.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

Parking garage where Bob Woodward met Watergate source "Deep Throat."

At 207 feet, one of the world's longest continuous escalators.

An Industrial Revolution-era public work that purified water using nothing but sand.

An easily overlooked memorial to a Ukrainian famine-genocide that killed over 4 million people.

Washington's iconic carousel has a nice piece of Civil Rights history.

The national park was once a plantation estate.

Look closely and you’ll notice that the color changes a third of the way up the tower.

A Dutch passageway's artistic, aquatic-themed makeover pays tribute to the capital city's famed waterways.

The walls of the iconic dome are hollow and have a secret stairway.

This seemingly out-of-place gas station by the Watergate hotel was once described as the most expensive gas station in the world.

Before Metro, Washington had a robust streetcar network—and you see the remains of this infrastructure if you know where to look.

This poor little statue is the most vandalized memorial in Washington.

Decades before the scandal, this staircase on the river was a literal "water gate."

A historic arena where the Beatles played their first concert in the U.S.

You could be standing at the site of one of D.C.'s most fatal tragedies and not even know it.

The most accurate timepiece in the world.

Fittingly, America's museum of architecture is itself a magnificently designed old building.