The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

The lowest point in North America is home to an undrinkable pool surrounded by fields of geometric salt flats.

"Only the devil could play golf here."

Quite simply the largest tree in the world (by volume).

A muscular Art Deco monument represents the struggle between regulators and unbridled markets.

The controversial urban planner who designed Washington, D.C., was buried in Maryland, and can presently be found in Virginia.

"Where the ducks walk on fish."

Faces carved into the cliffs create an otherworldly walking trail.

The last holdout of a pre-Civil War rebel who took the matter of slavery into his own hands.

Step back into the glory days of Florida's nascent tourism industry at this Gilded Age palace.

See massive fossils that are over 200 million years old in northeastern Arizona.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

This giant temperature attraction created some giant electric bills.

This private residence was the template for one of the most beloved television homes of all time.

Concrete strongholds stand guard over the Golden Gate.

Canyon walls shrouded in ferns.

The world's longest known cave system.

The granddaddy of all tourist traps, built on ice water, jackalopes, and a giant dinosaur.

Equal parts record-breaking temple to consumerism and bizarre fun park, it's more than you think it is...

A Mexican Romeo-and-Juliet-esque legend has given this super-narrow alleyway a reputation for romance.

Mexico's astounding mummy museum with "the world's smallest mummy."

The tallest The Church of Jesus Christ of Latter-day Saints temple in the world soars above the Beltway.

These unusual rooms on wheels are holdovers from the 1960s.

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