Upgrading building shoud be here, i have invented a new type of farms, it will be nic to have a posibility to upgrade them, just to conserv building space, and have a patch to build small expert towns with tall magic towers and great city hall, than a flatland pack of schools, and houses. Also posobility to add a building to existing tile will be nic, like in Dark Colony Strategy, Imagine, 3 big towers packed with schoolars, machineshops, alchemst labs, and breedings lairs undeneath ruling a land, Like towers of saruman.