Portland's Shanghai Tunnels are a network of passages running beneath the streets of Old Town, originally used as storage corridors connecting the basements of the hotels and saloons that lined the waterfront district. Tour operators run guided walking tours that descend into the tunnels and cover the history of the neighbourhood, the documented crimping trade (the Victorian-era system of debt bondage that supplied labour to ships), and the tunnels' later history as gambling dens and speakeasies.
Tours depart from the Hobo's Restaurant on SW 3rd Avenue and run on weekend evenings. They're two hours, require advance booking, and include a visit to the actual tunnels plus the adjacent areas. The guides are performance-oriented — the atmosphere is more theatrical than academic — but the history is broadly accurate and the physical space is genuinely interesting. Not suitable for those with mobility issues or severe claustrophobia.