Freight Broker Live guy was just playing a clip from last night in Portland, and the streamer was talking about an extensive tunnel system underneath the Justice Center. Part of the Shanghai Tunnel system. Someone streaming in Seattle said the same thing one night about tunnels under the police station that had been taken over.
Apparently Chinese immigrants dug tunnel systems under many U.S. cities back in the 1800's, for smuggling, kidnapping, opium dens, etc. Try searching for 'Shanghai Tunnels', and pick a random city. Many articles about them.