Subterranean Sites

Formerly abandoned underground complex to keep royals safe from a nuclear war that never came.

A brick foundation and piles of listing building materials are all that remains of this World War II POW camp.

Walk over a 150 year old manhole.

Five miles of underground river link lake to ocean.

This impressive tunnel was dug entirely by hand over the course of 36 years.

The only remnant of a small mining town is an abandoned railroad tunnel that is steeped in ghostly lore.

NYC's legendary underground network for bovine transportation.

The former locus of Boston's high culture has been shuttered and buried for over 70 years.

The world's largest man-made underground caverns offer unparalleled underwater wonders.

A tunnel once abandoned now thrives with graffiti art as an off-limits makeshift gallery.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

This long, dark tunnel is open to hikers, but those without lights are known to get confused even on the straight path.

An underground magnet for ever-changing street art.

Figures of unknown origin carved into the surfaces of underground caves.

The first full-scale tunnel built in America is short but scenic.

A unique Tuscan hideaway acts as an art mecca as well as a hotel.

This series of Scottish caves has no clear purpose other than baffling historians.

Below a historic English market town lies a secret underground city complete with kitchens, laundries, storerooms, and an underground lake.