I'm already part of a "still in the planning stages" commune but I will say this:

concrete dome homes.

they are indestructible.

look into it if you're building from scratch.

You'll need a lot of gardeners to keep you supplied with food.
You'll want a source of electricity - wind or solar?
You'll need fresh water, try to get a property where you are near many water sources.

Careful of coastal areas, what with global warming being what it is.