These structures were inspired by both Native American shelters as well as, strangely, an ice cream shop.

The Route 66 institution that inspired Taco Bell also served as an important headquarters for Mexican-American social movements.

The word "Watergate" will forever be associated with the infamous scandal in 1972, but this fountain is famous in its own right.

The final resting place of many of New Jersey's most famous residents, including U.S. history's most in-vogue antagonist, Aaron Burr.

A hidden passageway now marks the site of an assassination attempt on Ronald Reagan that some say broke a 140-year-old curse.

The most decorated dog of World War I is preserved in the Smithsonian.

A replica of the flagpole that gave a frontier town its name.

This temple, built by an eccentric religious leader before his death, sits guarded and in ruins.

The final resting place of the businessman-turned-astronomer who helped discover Pluto stands near his observatory.

A planet-hunting astrograph built in the 1920s to seek out the so-called "Planet X" beyond Uranus.

This Arizona observatory is famous for investigations into Martian life, and as the place humans first spotted Pluto.

An important piece of history from mankind's journey to the moon sits in the lobby of a government science lab.

A hoard of sky catalogs, astrophysical journals, even the works of Galileo and Copernicus.

A tribute to the pop culture icon overlooks this Washington D.C. intersection.

A memorial to a shareholder activist feared by CEOs around the United States.

A benevolent, 16-foot-tall river dragon lives on a suburban lawn.

Hidden within an idyllic suburban garden is a memorial dedicated to the victims of a terrifying spree of killings committed on U.S. soil.

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

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

An obscure federal monument honors the French diplomat who served as Ambassador to the U.S. during WWI.

Washington's top-secret Cold War-era doomsday communications tower is located in a small neighborhood park.

The whole world in one water tank.

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

The 72-foot giant escaped confinement in a large patch of mulch only to be reburied in the sandy shores of the Potomac River.