Another example: the Duke of Westminster is worth $12B and owns a large chunk of London outright, including a ton of large, notable buildings. (Also, I think, the Twinings tea company.)
There's the Crown Estate, which is controlled by the crown, but the family also owns the Duchy of Cornwall (45K acres) and the Duchy of Lancaster (45K acres), as well as numerous private holdings that are less visible. And this is predominantly highly developed city space.