Valkrionn
The Hamster King
after my new city was converted by loki to balseraphs, i conquired it after like 50 turns back and than something strange happened: city gained legendary culture, expanded the borders and stayed like that for quite long before just falling down back to 0 culture.
Most likely, city had negative culture, and then when it got back up to positive the borders shrunk. Need to check on that though.