About cities.

Hello, friends! I've been playing Heroes ("The Shadow of Death") for several years and have won almost all the single-player games and some campaigns without any tricks. At the same time, I always wondered - I have 8 cities to choose from: Rampart, Castle, Swamp, Stronghold, Inferno, Tower, Dungeon, and of course, Necropolis - why don't I have other factions, for example, where elementals or thieves, trolls, etc. live? Why do these creatures appear in the game, but I can't build the corresponding cities???? What needs to be done to add more cities to my version of the game, or can they be downloaded from somewhere?