All right, how do you get a genuine imaginary city?
Beats me, except possibly by picking this list up. The contents are quite simple, a list of an hundred plausible-sounding names sounding like they come from an assortment of cultures, ready for you to use as you plan your new campaign world, or just need a likely-sounding hometown for an NPC...
Some are recognisable. Beersheba is found in the Scriptures (at least, if the Old Testament of the Bible is sacred to you). Llaregub was invented by the Welsh poet Dylan Thomas and for best effect is read alound backwards... Lubec is a real place if you add a 'k' on the end.
Maybe that's why they sound so real. Try typing a few into Google or chucking them into a geographical quiz... or just use them for the purpose intended and put them on your campaign map. They will soon cease to be imaginary, at least as far as your alternate reality is concerned.