Subterranean Sites

A gateway to a mysterious network of underground tunnels.

This 1000 year old relic-filled cave monastery and UNESCO World Heritage Site also hosts an amazing micro-miniature museum.

The last fully functional fortress of Germany's World War II Atlantikwall.

Hideout of thieves, monks, and goat-footed gods.

In the middle of downtown Brooklyn lies a 165 year old secret hidden right below the surface (closed to the public indefinitely).

An Aztec temple, the largest man-made pyramid in the world, sits buried in earth with a Spanish church set on top.

The largest of London's subterranean rivers and once a mad, bad center of London life.

Ancient man-made caves underneath small town Belgium.

Abandoned railroad tunnel is home to a colony of three million Mexican free-tail bats.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

The biggest solar telescope in the world helps reveal the secrets of our sun.

An ancient capital city that dates back 3,000 years old and harbors many surprises.

Virgil's many-mouthed gateway to the underworld.

A tunnel of hardened lava along Maui’s famous Road to Hana.

Potential high level nuclear waste storage site for the next 10,000 years and beyond.

Step into the cool deep past and unknown future of who begat who.

The world's second largest salt mine, said to have been discovered by Alexander the Great's horse.

Concrete strongholds stand guard over the Golden Gate.