This 18th-century folly is one of Europe's rare "garden mosques."

This inconspicuous pharmacy went down in history as the first gas station in the world after fueling the first road trip ever taken.

The entire length of the border is marked by a 20-foot-wide slash through the trees.

The world's largest fully steerable radio telescope.

This rural community has attracted both scientists and techno-refugees due to its federally-mandated lack of technology.

This hotel was used during the Manhattan Project to house official visitors.

John Hendrix predicted the creation of the "Secret City" built as part of the Manhattan Project.

One of the Cemestos prefab homes built to secretly house thousands of Manhattan Project workers.

The secret city built by the Manhattan Project.

Explore the largest pure gypsum deposit in the world, and go dune sledding while you're at it.

Twice a year, visitors can tour the desolate site that birthed the Atomic Age.

The Decoy Capital of the World.

A total of 14 men held the title of "president" before George Washington—their historical legacies are enshrined in the lobby of a hotel.

A Maryland museum dedicated to Black history, housed in a historic church.

This statue honors the author's groundbreaking family story.

This 16-foot, intricately detailed model of the Gearing-class destroyer has been called the most detailed model ship ever built.

Bermuda triangle lighthouse, site of mysterious disappearances, left to crumble into the Atlantic.

In the Bahamas sits a lighthouse that is among the last of its kind.

This small island off the coast of Uruguay hosts the largest colony of sea lions and fur seals in the southern hemisphere.

This bustling Italian plaza is built on the ruins of an ancient Roman amphitheater.

The first botanical garden, a feather in the cap of the Grand Duke of Tuscany.

Next to the Leaning Tower of Pisa is a cemetery home to ancient sarcophagi and disturbing murals.

The only visible reminders of an elaborate engineering project that kept the tower from reaching the tipping point.

Secret refuge and museum of the Duke of Florence.