An apartment of over 500 m2 is enormous.
But an acre it is not, an acre being a little over 4000 m2.
Even the famous apartment of the mayor of Paris, at an alleged 1400 m2, is only about a third of an acre.
By comparison, Westminster Cathedral is about 2600 m2.
Perhaps more relevant, Parker Morris standards for housing suggest that 72 m2 should be enough for a family of four.
Clive Saville, London N5