Star City = Seattle
Central City = Minneapolis, Keystone = St. Paul
Coast City = San Francisco
Metropolis/Gotham = New York
But...there are versions of all these real world cities in the DCU as well.
Right. The thing is, DC's continuity for decades was a loose hodgepodge. It wasn't a single interconnected whole like the Marvel Universe, but a bunch of distinct, independent series that occasionally pretended to share a universe in crossover books like Justice League, but otherwise pretty much ignored each other and went their own separate, often conflicting ways. So Superman had its fictional version of New York, and Batman had its own distinct version, and then Teen Titans came along and used the actual New York, and they all just did their own thing. It was only later that any real effort was made to systematize them all into a consistent geography.