As the tunnels are filled, the walls will collapse, and the ground above will fill them.
That should slow the rats down a bit.
i’ve seen many reports and images that show the tunnels are constructed of concrete .... courtesy of U.S. taxpayers ...
“As the tunnels are filled, the walls will collapse, and the ground above will fill them.”
I doubt the walls will collapse. The ceilings are rounded. So they’ll probably be like the Roman cisterns. Will just be tunnels full of water. Some may collapse if they’ve been compromised somewhere by bombs etc.