Or quite a few religious organizations.

The whole reason why the Catholic Church doesn't allow priests to be married anymore was because it used to be that the individual churches were mostly the property of the priest, and would be passed down generationally (with some restrictions). The church phased in the ban on marriage so that over time, the churches would all in up in the estate of a priest with no heirs, where they'd become the property more formally of the Catholic Church proper. Today the Catholic Church is the single largest landowner in the world, with about 170 million acres.

More recent religious organizations have taken note of that, with LDS owning about 2.4M acres.

Duke: A healthcare system with a little University.