The universally beloved children's television figure is interred on a high hilltop in one of western Pennsylvania's oldest cemeteries.

A larger-than-life statue of America's favorite sundae marks the place it was invented.

A tradition unlike any other, this marks the site of the annual Groundhog's Day tradition.

One day a year it is legal to jump off of this astoundingly tall bridge that spans an Appalachian gorge.

The "mysteries" of this quintessential roadside oddity were almost destroyed by neglect but were saved by fans of kitschy wonder.

This rural community has attracted both scientists and techno-refugees due to its federally-mandated lack of technology.

The world's largest fully steerable radio telescope.

Take a steam-powered ride straight out of the past on this Appalachian rail line.

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

A historic estate packed with George Washington's heirlooms, and its own nuclear bunker.

Helen Keller once broke ground on this historic center for the study of technologies to benefit the hearing impaired.

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

Daredevil repair workers can worm their way out the access hatch, loop ropes over the apex and rappel down the monument.

The U.S. Fish Commission’s effort to mass produce carp.

The grand marble structure next to the White House is Andrew Carnegie's temple to Pan-American diplomacy.

Seemingly unremarkable items like empty sushi trays, chef hats, and freshness stickers are being preserved so future generations can look back on this beloved cultural import.

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

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

This mysterious structure by the Washington Monument is a flood barrier designed to protect the White House against rising waters.

The Pentagon sits on a former island that was in Virginia at low tide and D.C. at high tide.

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

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

The famous abolitionist’s preserved estate is one of Washington's finest monuments to its great Black citizens.

A super-sized promotional trick that is now a D.C. landmark.