A subterranean shelter remains intact under a busy Paris railway station.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

These crumbling Nazi artillery bunkers are now fair game for massive graffiti projects.

This abandoned Belgian fortress is purposefully being left to nature.

Part modern art project, part traditional chapel, this see-through church is only substantial from the right angle.

This enormous storm barrier is one of the largest moving structures on Earth, with each arm taller than the Washington Monument.

The vast chamber inside this abandoned cooling tower looks like something out of a sci-fi dystopia.