There are three towns in the old city.
Bridgetown is exactly that: it was built on the section of the highway bridge that the air force left standing, and part of the onramps. The only access is by ladder or pulley elevator. About five hundred people live there.
The other two towns are blocks of buildings, bricked off at street level, connected by ramps and knocked-out firewalls, numbering about three hundred each.
There was a fourth, protected by fences and trenches. They ran short of supplies, turned to raiding parties out of desperation, and the other three burned them out.