Originally Posted by
Ordensritter
In order to do this, you have to look for the export_descr_buildings. Can be found at vanilla/DLV_ext/data and open it.
For cites search this line and delete the red marked part.
huge_stone_wall city requires factions { northern_european, mesoamerican, middle_eastern, eastern_european, greek, southern_european, } and hidden_resource metropolis
For citadels search this line and delete the red marked part, too.
citadel castle requires factions { northern_european, mesoamerican, middle_eastern, eastern_european, greek, southern_european, } and hidden_resource metropolis