Do fortressess have practical value was a question in this thread.
Well Kramnik just saved game 7 with a fortress.
After Kxc3 white has no entry points.
Just note that white can do nothing on the kingside.
If white transfers his king to say g2 or g3 and follows up with h4,
black need not react.
After hxg5 he closes the kingside with g6, when even two extra pawns dont mean a thing.
while after h5 white has locked himself out.
Actually a side variation could produce a similar fortress.
From the following position:
32.bxa5 (iso 32.b5 as played by Anand)
32........, bxa5
33.Rb1 , Nc5
34.Bxc5 , Rc5
35.Rc1 , Kf7!
36.e4 With the plan Ke3-d4 etc
36...., c3!
37.Kd3, c2!
38.Rxc2,Rxc2
39.Kxc2,Ke7!
Again a
fortress has appeared on the board.
Black has only to take a minimum of care.
He is just in time to answer Kc4 or Kd4 with Kc6 or Kb6
and he can pendle between c6 and b6 without any problem.