Why can't I build a campus in the middle of these mountains?

Some items of note: I harvested some stone off of that tile. I annexed the tile into my city using a great merchant that allows me to do so.

1 Answer

You can only build districts in a 3 tile radius around your city, and that tile is 4 tiles away.

(Civ6)

You cannot place districts in other cities' territory, even if these other cities belong to you and the tile in question is up to three tiles away from the City Center