Tunnels

The labyrinthine storm tunnels beneath the city of Melbourne are ruled by a band of urban explorers.

This narrow path was cut right into a French mountainside to feed the country's early naval expansion.

One of the few standing Roman lighthouses and a labyrinth of tunnels are a couple of the secrets at this historic castle.

Once the path of a railway tunnel, now home to thousands of glowing insects.

It should come as no surprise that the best view of the Hollywood sign is from Batman's lair.

An underground city of ancient quarry tunnels hid thousands of Allied soldiers in WWI.

Underneath a chalk hill in France lies what Hitler hoped would be the underground launching base for a devastating new weapon.

A former copper mine which became a truly unsuccessful prison.

An open-air sewer system that was covered piece-by-piece over 300 years.

This museum preserves the hand-dug tunnel that kept Sarajevo afloat during the Serbian siege.

What was once an underground Nazi city is now Europe's largest bat reserve.

Beijing's expansive subterranean hiding spot now crumbles away as a tourist destination.

Behind this beachfront shop lies a spectacular, colorful sea cave with an equally colorful past.

These medieval tunnels provided water to the city above through centuries of civil war and plague.

One man's real life disfigurement inspired a lasting local legend surrounding an eerie tunnel.

An unfinished rail tunnel that has since been used to house cheese and bats.