The remains of a historic plantation nestled in between a parking lot and the rental car return at Reagan National Airport.

This propitious plastic porcine has been petitioning park visitors to pick up after themselves for more than 50 years.

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

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

This grave marks the passing of a historic Jane Doe whose identity remains a mystery to this day.

This "castle" is actually a limestone and quartz formation hidden along a trail.

A gift from Scotland to the United States in memory of the 270 lives lost when Pan Am Flight 103 exploded over Lockerbie due to a terrorist bombing.

Born a slave on the Arlington estate, Parks dug the first graves at Arlington National Cemetery, and was buried there, too.

The system of air guns are fired off remotely to scare any trespassing avians.

This stately building in Alexandria, Virginia was built by Freemasons to honor one of their most famous members.

The tomb was guarded by soldiers from both sides of the war, and some left their initials carved in the brick.

This brick-lined pedestrian walkway was once a railway tunnel used during the Civil War.

The final resting place of an unidentified revolutionary soldier sits behind a Virginia church.

This twice-relocated "Usonian" home is among the smallest built by master architect Frank Lloyd Wright.

A gazebo that inspired the fifth episode of the "Twilight Zone" still stands in the creator's hometown

Visitors to Salt Springs State Park are encouraged to literally put their two cents in Penny Rock.

A 16th-century horror show built in a lovely Italian garden.

These expertly crafted, scientifically accurate glass sea creatures were once an international phenomenon.

This exhibit allows visitors to wander through the interior of a replica Ice Age glacial cave.

Corn-inthian columns with a uniquely American take on neoclassical architecture.

A clone of a cloned tree that was so important it allegedly had its own guards.

The bank that helped fund the Mexican-American War and the purchase of Alaska met its downfall after helping Augusto Pinochet launder money.

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