Introduction

Historians, engineers, ​and experts take a look at the underground structures, systems, and phenomena that exist beneath our feet.

Outline

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.

Underground Marvels Series

• Episode 01: Secrets of the Rock.
• Episode 03: Secrets of the Terror Tunnels.

Production & Filming Details

• Release Date: 17 October 2019 (US).
• Running Time: 60 minutes.
• Country: UK.
• Language: English.

YouTube Link