The first declared National Monument in the United States.

Yes, this monument is aware that it is about 20 miles away from the actual center of the United States.

The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

An architect's childhood fantasy treehouse made real.

The only natural lake in the world that drains into both the Atlantic and Pacific Oceans.

The high point on the 16th president's eponymous roadway is marked by a massive version of his head.

Miraculous tree that seems to sprout out of solid rock.

A monument to the egos of two railroad magnates that fell into decline along with their careers.

World's most expensive home.

Follow the steps, and this roadside artwork will teach you how to dance.

Once a mortuary that held the remains of Buffalo Bill, this Denver hotspot is now a death-fixated restaurant.

A stark reminder of the huge nuclear weapons plant that once stood on the site and its effect on the surrounding area.

The remains of an entire Roman city can be explored in this interactive museum.

This Slovakian statue of an emerging sewer worker might just be a bronze peeping tom.

This Slovak bridge is known both for its connection to a national uprising and its UFO-shaped eatery.

This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

A statue in Budapest's Liberty Square honors the former U.S. president's efforts to end the Cold War.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

Possibly the world's largest hourglass only needs to be reset every New Year's Eve.

The geographical center of Budapest is marked with a 10-foot-tall stylized zero.

This statue of a falling man commemorates a teenage martyr of the Hungarian Revolution.

A museum dedicated to a secret military hospital hidden beneath a castle in Budapest.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.