This giant, 83-year-old ship elevator is an engineering feat to behold.

This long-distance walking route follows the Prime Meridian line as it passes through England.

The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

Kentucky, Tennessee, and Virginia meet at this point in the Cumberland Gap.

The first American home of the isolated, egalitarian religion has a trove of Shaker architecture and artifacts.

An important landmark in the history of algebraic logic.

For over 100 years, this Indiana town has had a tree growing out the top of the local courthouse.

The stone marker that Mason and Dixon placed at the eastern end of the famous north-south border they surveyed.

A single handprint, which, according to Ohio State University legend, cannot be scrubbed off.

A line of blue paint marks the route of the inaugural parade.

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

A small triangle of DC grass is the final resting place of one of Sonny and Cher's songs.

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

The house where John Wilkes Booth conspired with his co-conspirators.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

America's Most Wanted's set resides in this tribute to the history of crime and punishment.

This grand gothic brewery has been pumping out suds for over a hundred years.

Home to items never before seen by the public.

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.

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

A portal into the bricked up canal that runs through the heart of Washington D.C.

A pop-culture attraction outside of Dyersville, Iowa, hits a home run.

A mysterious monument where a woman who records say never existed was burnt alive for being a witch.

This unique bridge physically lifts a piece of the road into the air to let boats pass by.