This beautifully verdant lagoon is tucked below a massive volcano in a crater atop a black pebble beach.

Home to the largest urban bat colony in North America, estimated at 1.5 million bats.

Continuing the tradition of the dime museum in style.

This eclectic Austin curiosity shop is home to all things strange and unusual.

This military tunnel dates back to World War II and provides visitors with a little wartime adrenaline.

An eclectic art form practiced by untrained masters is celebrated at this museum in the heart of Zagreb's old Upper Town.

A full figure 4th century incorruptible saint lies in a glass coffin in Croatia.

Now abandoned, the world's first torpedo factory is crumbling into the sea.

When Croatia became independent of Yugoslavia, the splintering governments left behind these concrete tunnels.

A wunderkammer of gold and silver reliquaries and ancient saintly bones.

The now-overgrown beach resort was once frequented by Yugoslav military elite.

This former estate of a fascist leader is now a burnt out ruin leading to a system of secret tunnels.

This picturesque medieval monastery guards a small trove of historic treasures.

This Croatian fairytale castle is slowly falling apart thanks to years of neglect.

This huge metal monument is slowly being stripped to its concrete skeleton.

Once a state-of-the-art tuberculosis treatment spa, these ruins are now ruled by paintball players.

The complex has been abandoned since the Croatian War of Independence, barring a stint as a set for 'Game of Thrones.'

Legend has it fairies gathered at the site of this medieval castle.

The remains of a sunken military ship wreck visible through clear water.

This truly palatial work of Communist-era architecture now sits crumbling on a Croatian beach.

Large, airy hallways hide within an impenetrable fortress that beckons urban explorers.

A wonderfully strange collection of 500+ stuffed frogs doing people things.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

An ethereal glowing blue ocean cave in Croatia.