Subterranean Sites

This hidden stream beneath Indianapolis makes an appearance in the best-selling novel "Underground Airlines."

Wild lights and sound effects turn a walk through some caves into an eye-popping 1960s tourist attraction.

Underground tunnels once home to crime are now back open to the public.

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

An ancient tunnel in Jerusalem built to redirect water in the event of a siege is one of history’s great architectural innovations.

A town church once nearly submerged by the damming of a river is now hauntingly visible as the water recedes.

Welcome to old Florida, where a 1940s mermaid show is still enchanting visitors.

Inhospitable caverns just beneath this island paradise offer insights into alien worlds.

Stay in a room with a view... of the bottom of the ocean.

The hidden "ballroom" under a mansion lake was built by a criminal who ate a cyanide pill during his trial.

For divers and music lovers, the Florida Keys' Underwater Music Festival provides the best of both worlds.

This railroad tunnel was once the longest in Massachusetts.

This road in the Great Smoky Mountains was supposed to assuage a displaced community, but ended up a $52 million dead end.

Parking garage where Bob Woodward met Watergate source "Deep Throat."

A 90-year-old underground water reservoir offers a more industrial kind of tranquility.