when you build a new base, you can just select where you want it and it is built there. we could add some realism here...
it should not be possible to build a base right next to big cities
(our little alien defence agency is a secret organization, after all)
high mountains are right out
(building a base at the top of mount everest? c'mon.)
regions with high tectonic activity including nearby volcanos should be limited at least
(our bases are underground, remember? imagine fighting aliens from above and lava from below at the same time...)
I'm sure there's more.
So my idea would be like this: You tell the game where you want a new base. The game checks on some kind of invisible map and tells you (maybe after a few days of research?) "okay sir, we have located the following x spots in the area you selected where it is possible for us to build a base. choose the one you like"
another idea by julian was
Rather than limit the possible locations how about we make it into the spying system. See: Wouldn't it be easier for aliens to find the location of your base if it was near a big city?
(topic originally discussed in http://www.xcomufo.c...?showtopic=4457 )