Underground passage for transportation or utilities.
InfrastructureEngineeringTransportationConstruction
Current best complexity is 6:
Tunnel can be discovered in Concepts, categorized under Infrastructure, Engineering, Transportation, Construction. Underground passage for transportation or utilities.
It has been discovered by 27 boards and crafted 90 times, first appearing 5 months ago. Tunnel can be created from 59 recipes, and goes on to appear as an ingredient in 199 others.
Tunnel was first discovered by Federico's board 5 months ago. The lowest-complexity recipe (6) is held by secret.
Related concepts worth exploring include Brick, Wall, Dam, Wind Tunnel, Skyscraper, Steam Engine, and 6 more.