Also known as the Founding Church of Scientology.

A tiny monument to the unsuccessful attempt by Thomas Jefferson to place the prime meridian in Washington.

This unacceptably tall building was the real reason for Washington, D.C.'s skyscraper ban.

A much-maligned monument to teetotalism.

The most accurate timepiece in the world.

Housing the National Women's Party since 1929, this historic house is now a monument to the fight for gender equality.

A painfully obvious spy house sits right across the street from the Russian Embassy.

One of the dwarven trees dates back to 1625 and survived the Hiroshima bombing.

The site of the climactic scene from the classic horror film is now a historic landmark.

This four-story steel sphere in Maryland was used to test biological weapons.

The childhood home of the Sultan of Swat is just a line drive away from Oriole Park at Camden Yards.

A relic of FDR's brief foray into utopian urban planning.

An isolated island home to one of the oldest English-speaking communities in the region and Maryland's state dessert.

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

Once home to seven different roller coasters, Glen Echo has undergone many transformations since its founding in 1891.

A 200-year-old bar with a cheeky name claims to have served Edgar Allan Poe his final drink.

Wedged between two sets of row houses is an awkwardly located family graveyard.

The trials and tribulations of marking Poe's grave.

Crystal clear lake with a shoreline of travertine located in a Colorado canyon.

This is one really big nut.

This fast-food outlet is the only space and UFO-themed McDonalds in the world.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

Explore the largest pure gypsum deposit in the world, and go dune sledding while you're at it.

"May the force be with you always."