Underground cities have the exact same coordinates as their surface counterparts (I was curious myself to see where I would end up each time). The idea for the mausoleum and wings is interesting and worth implementing. Regarding artifacts, it's completely random; if anything needs to be changed, it would have to be that everyone gets the same artifacts. Your suggestions regarding teleports are unclear. Currently, it's set up so that you can't teleport anywhere from the "main" city, and from the estate, you can only teleport to the main city (if you're on your territory). What do you want to change?