Despite the name, these small saltwater swimming pools have nothing to do with the Romans.

Ancient mysterious ruts carved in the bedrock.

This 50-foot-deep sinkhole created in the 14th century is home to rare plants and fungi.

This prison on the Maltese island of Gozo is almost 500 years old, and they have the graffiti to prove it.

An ancient burial ground believed to have been used for ritual sacrifice.

The best-preserved Roman small town in North Africa.

This subterranean necropolis holds three floors of antler-dug grave caves.

This almost-forgotten underground dungeon housed several convicts over the years, including Caravaggio.

A working miniature city designed to teach kids about safety and presumably city planning.

The former home of the army detachment that captured Geronimo.

Get a taste of Chamorro cuisine, family-style, at this popular restaurant.

This Great Plains museum pays tribute to both the prosperity and tragedy of the North American fur trade.

Site of the 1879 Cheyenne Outbreak and the site where famed Sioux chief Crazy Horse met his fate.

These boots are made for selfies.

Three hundred years of preserved Spanish colonial history in San Antonio.

The oldest active mini golf course in the U.S. has an elegant Art Deco style filled with lush tropical plants.

Craggy concrete faces are hidden in the walls of this artificial cave along the San Antonio River.

The remains of an ancient Roman city are hidden underneath Bologna's beautiful public library.

An Albanian monument to the Communism that nearly crushed the country is now a crumbling wreck.

In the heart of Tirana, this underground nuclear bunker has been transformed into a museum.

Decorated with a staggering 1,380 ladybugs, the installation has turned what was once a grim, forgotten nickel mine into a landmark and a statement.

A historical puzzle lies at the origins of this structure.

Despite time, colonization, and the brutal New Mexican heat, these Pueblo ruins still stand.

The remains of a historic ranch house that witnessed the Civil War battle dubbed the “Gettysburg of the West.”