>>2059050Because the foundation of the city is mud, not rock. It's all river and glacial sediment projecting into the Adriatic basin.
The buildings themselves are built on tree-trunks hammered into the mud until resistance was too high to hammer them farther. They are not sitting on bedrock or anything, they are basically free-floating in the mud.
https://www.bbc.com/future/article/20250324-the-ancient-forest-that-supports-veniceMaybe you could dig a metro deep enough to actually put it in the bedrock? I'm not familiar with the specific geology of the area. But if you systematically disturb the mud that all these buildings are floating on (for example, from vibrations and subsidence due to the tunnel), then you are going to destroy whole strips of the city. And never mind the destruction from digging out the stations.
Also, has anyone actually built metro stations under water? I mean, maybe it has happened somewhere in the world, but it's not exactly an easy problem building the cofferdams, draining and hollowing them them out, and keeping the work area from flooding as you dig to meet the tunnel.
