Huge abstract sculptures of the Puerto Rican Flag.

These mansions date back to Chicago's days as a brewer's paradise.

Located within a historic park, the beacon is the oldest standing structure in Miami.

A three-story tower of books about Abraham Lincoln is one of the more unusual monuments to the president.

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

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

This colonial tavern played host to George Washington, Thomas Jefferson, and other famous early Americans.

Down the road from where the Wright brothers lifted off is another flight tribute practically hidden from sight in the woods.

The remains of a Rockefeller's lush Italianate estate hidden in the underbrush on the coast of Lake Michigan.

This sprawling mini-golf empire is an impressive testament to a disappearing attraction.

Shop of curiosities with a dinosaur museum tucked in its basement.

More than 8,000 drinking jugs say “Cheers!” to a guy named Toby.

Recognized the world over as the home of the McCallisters in the 1990 movie "Home Alone."

A collection of artifacts from Maryland's maritime past.

Baltimore's classic clock tower was once topped by a rotating, 20-ton medicine bottle.

Bizarre Cavern.

A Chicago Movie Palace Lost to Time.

Every drop of D.C. tap water flows through this old waterworks.

The little-known, 300-year history of the area includes former lives as a bustling tobacco port, parking lot, and industrial dump.

While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

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

The span is crooked and made from two older recycled bridges.

The unique traffic pattern named for an influential urban planner is also known as the Pedestrian Scramble.

Daily lunch spot for many of Washington, D.C.'s cab drivers.