The "Bridge Over the Atlantic" lets you cross the waterway in mere seconds.

An abandoned facility that has become a place of ritualistic satanic worship, or so rumor has it.

The world's largest model of our planetary system.

This park was designated by UNESCO as an Endangered World Heritage site.

This abandoned Victorian-style house was built in 1884.

An architectural gem nestled into a promontory overlooking a prehistoric landscape.

This mysterious petroglyph evokes the ancient swastika symbol but was later vandalized with the more troublesome Nazi one.

The largest earthwork effigy in the world.

A coastal rock outcrop with mysterious inscriptions variously attributed to Native Americans, Portuguese, Phoenicians, Norse, and more.

Native Americans built this circle of stones, which was used to predict astronomical events.

Mysterious ancient boulder carved with petroglyphs in the mountains of Western North Carolina.

Ancient human, animal, and geometric figures drawn in the earth.

America's oldest archaeological site or a muddled case of wishful thinking.

One of ancient Etruria's most spectacular archaeological sites with impressive necropolises and rugged landscape.

This lesser-known leaning tower is all that remains of the medieval castle of Vernazzano.

These layered sandstone mountains in China look like they are made of pressed crayons.

A sinkhole and now a swimming hole, too, full of dazzling turquoise water.

Climb down into the largest sinkhole in Qatar.

Romania's "Red Ravine" is a little-known natural wonder that bears a resemblance to the Grand Canyon.

A grove of "candelabra redwoods" deep in California's Lost Coast.

A secluded, little-known temple hidden amid the dense jungle.

The only remaining arch of the oldest stone bridge in Rome stands in the middle of the Tiber.

In the early Roman Empire, people deemed traitors and criminals were tossed to their deaths from this rock.

This lighthouse was crafted as penitence for the theft of wine bound for a monastery.