Monopoly As Stated

EconoPundit says:

...as long as markets are theoretically contestable, monopolists invariably price as if competition were a present reality (that is the reason, incidentally, that Wal-Mart doesn't jack up prices once its competitors are neutralized; it doesn't want to tempt others into the market).

He's right; not that that helped Alcoa, thougn, back when it did everything it could to remain competitive and fair to its consumers, only to have Judge Learned Hand hang them high for it anyway.

Has there ever been a long-term monopoly that held together without state support?