If I remember correctly, courthouses are always destroyed when a city is conquered. On the other hand, when a civ loses one of their cities and then conquers it again, it does not have to build a courthouse there.
My question is, does a city become "mine" after building a courthouse, e.g. if I lose and then re-conquer it, will I have to build a courthouse again? Or do all cities remember only the original civ that built them, and only that civ doesn't need a courthouse?