Ed:

Here in Spain fig trees are very common (I have three, one inside my garden
and two wild figs outside), and they are capable of great damage. Just a
brief anecdote: there was a court case we read about last week in the local
newspaper. One guy took his neighbour to court for damages in his garden
wall caused by the other man's fig tree. The amazing thing is that the tree
stands about 90 metres away.
My tree is now about 12 years old, stands around 14 feet high, and between
the wasps, the starlings and my wife we get about 300 figs each season. It
has however done considerable damage to my brick wall.
The concrete slabs in the ground are a good suggestion. Remember to seal the
corners with cement or the roots will be out through there and away.
Paul.