Subterranean Sites

This subterranean necropolis holds three floors of antler-dug grave caves.

This small city where almost everyone lives in the same building can only be reached via North America's longest tunnel.

Running under an entire mountain, the longest highway tunnel in North America is kept fresh using portal fans and jet fans.

This angular Dwarven tunnel cuts through a mountainside in Glacier National Park.

These sub-farmland caves are home to a majestic stalactite known as the "Crystal King."

This Italian foot path winds through the mountains via 52 individual tunnels.

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

Formerly Yugoslavia's "forbidden island," this sleepy little city still holds the abandoned remains of military strongholds.

To literally keep their waste out of their own backyards, the citizens of this English city built an impressive sewer system that is still in use today.

This series of underground chambers contains Europe's largest subterranean lake that is slowly drained each day.

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

This remarkable cave was discovered after a shepherd watched bees enter and exit through a small fissure.

The longest navigable underground river in the United States is home to countless blind and albino animals.

This former limestone quarry is now a subterranean wonderland of grand stonework.