A jungle cave in Peru of unknown depths, otherworldly sounds, and strange nocturnal birds that navigate by echolocation.

The world's fifth tallest waterfall is a spectacular silver chute of water that cuts through the cloud forest in northern Peru.

These steeply terraced ruins are a stop along the Inca Trail to Machu Picchu.

The largest-known fragment of an asteroid that exploded over the southern Ural region in 2013.

A throwback to 1980's gaming nostalgia.

An average of 33 million gallons of water pour out of the collapsed cave at the heart of this spherical spring.

Minnesota's highest point is a scenic vista marked by a plaque and armies of mosquitoes.

Journey through the largest remaining peat bogs in the contiguous United States to see the wilderness as it once was.

A warehouse for all of your architectural details.

A spooky defunct railroad tunnel now part of a sprawling trail.

A riverside park built around the ruins of a massive dam that collapsed in 1909.

When flour explodes, it's not a pretty sight.

An abandoned castle owned and ignored by Masons carries a cursed history.

This castle was established by the 4th Duke of Montrose and is connected to the Buchanan Clan.

European castle ruins in an American state park are actually the product of death and grief.

The ruins of this gorgeous clifftop castle look like something from a fantasy novel.

A medieval castle in the middle of rural Texas.

A 15-foot-tall statue of the head of the Sopranos family greets passengers at a train station in southeastern Lithuania.

The largest underground lake in Europe.

In the middle of a Vienna square, Roman ruins dating back some 2,000 years are on display.

Built for an exposition in 1915, these horticultural displays have stood the test of time.

Often referred to as the largest spring in America.

The deepest spring in Missouri.

An abandoned munitions storage facility with a rich architectural history.