This is in central Berlin, the net is just about visible: https://maps.app.goo.gl/vDSL4HeQrLLfYU2m7

Clifton Suspension Bridge in the UK is infamous for it, which is why it's now got a barrier up on the pedestrian section: https://maps.app.goo.gl/U1xYZHqhhxNoKMDV7

I think I saw one in Freiburg, in University. I vaguely remember seeing some nets in The Netherlands. Probably inside Science Park buildings.