Underground Marvels — Season 1, Episode 1: Secrets of the Rock
Documentary • 45 min • 2 seasons, 20 episodes • ★ 6.5/10
Episode synopsis
A hidden, subterranean city built within the Rock of Gibraltar was an immense fortress to control the seas during World War II, and new discoveries reveal the secrets of a long-lost chamber with evidence of high-stakes espionage.
About Underground Marvels
Historians, engineers, and experts take a look at the underground structures, systems, and phenomena that exist beneath our feet.