To unlock this property, build a house on any property. Of course, to do this, you'll need a monopoly on any color (I can't confirm that this trophy is unlockable with the "Property Improvements" House Rule).
Start a game with two players where you control both players. Trade whatever you need to Player One to get a monopoly. Once you have the monopoly, simply view your properties after your turn and go to the monopoly. At this point, build a house on any property to unlock this trophy.
This trophy is pretty similar to the "VIP" trophy. You might as well get that after doing this one.