Simply mass a "real estate empire". Easier than it sounds and the best way to get gold fast in Fable 2. Basically, what you need to do is buy and rent out every piece of architecture you can get your hands on; whether you up or lower the rent is up to you. Obviously if you up it, you'll get rich quicker and be able to expand quicker, BUT you'll be a evil, corrupt character.
Buying and renting is a great way to get a regular income of money and simply going to bed at night while your Xbox rests earns rent as well. So simply, buy, rent out and expand. It should not take you ALL the property in Albion for this achievement, but chances are, you'll need the castle because it's worth a million.
To check your current real estate value, go to Start > Logbook > Stats and scroll down some.
Significant Places to Buy:
Fairfax Castle - After the game is complete.
Cemetery Mansion - After the "Love Hurts" mission.
Father Gile's Farm (Brightwood) - After the "Blind Date" mission.
Garth's Tower - Sometime later on in the game.
Reaver's House - After the game is complete.