City of Naours
- Episode aired Oct 30, 2019
- 44m
An underground city beneath a forest in Northern France built to house 3,000 people, an ice cave under Iceland's biggest glacier, and a subterranean power station in London.An underground city beneath a forest in Northern France built to house 3,000 people, an ice cave under Iceland's biggest glacier, and a subterranean power station in London.An underground city beneath a forest in Northern France built to house 3,000 people, an ice cave under Iceland's biggest glacier, and a subterranean power station in London.