Built to give thanks for the passing of a plague epidemic, this cathedral is a one-of-a-kind architectural hybrid.

This column celebrates Rome's victory over the Goths, and may be the oldest Roman monument in Istanbul.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

This memorial to the victims of the Romanian Revolution of 1989 is often compared to a potato on a skewer.

A tribute to an iconic act of defiance from the Croatian War of Independence involving a small car.

This former New Jersey bus now exists as a public art exhibit.

Nature's biggest mammal swims in landlocked Oklahoma.

Standing at 21-feet tall, this space cowboy adds to the legacy of Route 66's muffler men.

On Waikīkī Beach, a monument to four extraordinary individuals of dual male and female spirits who brought the healing arts from Tahiti to Hawai'i.

Long before ultrasounds and modern testing, medical specimens like these conjoined twins helped physicians learn about congenital anomalies.

In the "Danish Capital of America," a replica of one of Copenhagen's most iconic buildings.

Once a meeting point for great thinkers, and the midpoint of the country.

The traveling wares of Denmark's most famous author.

The oldest Naval chapel in the United States is home to an incredible collection of Tiffany stained-glass windows.

This lakefront cottage was crafted in the 1800s and was once a sanitorium.

Home to the world's largest refracting telescope and the birthplace of modern astrophysics.

A non-native grove of 241 redwoods in Southern California.

This enormous World War II relic is one of the largest wooden structures in the world.

Where the polar bear watches over everything, and every drink is a double.

A historic hotel in an old California railroad town with a rowdy reputation.

The remains of a deserted steamboat sit rusting beside an old ferry pier and an abandoned train platform.

Napa's oldest building is now a Mexican restaurant.

A glass display case holds the document that ended the Second World War—which one person signed on the wrong line.

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