A World Championship Fortress

An unusual example of an endgame fortress occurred in the fourth game of the 2000 Braingames World Championship match. A tablebase confirms that the following position, where White has the advantage of a Knight and Pawn, is drawn with best play.

2000 World Championship Match (game 4)
Kasparov, Garry

Kramnik, Vladimir
(After 56.Rf7-g7(xP))
[FEN "8/2N3R1/Pk6/4r3/8/8/8/3K4 b - - 0 56"]

The game continued 56...Ra5 57.Kd2 Ra1 58.Kc2, which is still a theoretical draw, but now Kasparov erred with 58...Rh1. The draw requires keeping the Black Rook on the a-file. With 59.Rg8, Kramnik could have forced a win, but he played 59.Kb2, allowing Kasparov to escape the loss with 59...Rh8. After 60.Kb3 Rc8 61.a7 Kxa7, the position simplified into the well known and easily drawn Rook and Knight vs. Rook endgame.

To play through the complete game see...

Vladimir Kramnik vs Garry Kasparov; World Championship Match 2000
http://www.chessgames.com/perl/chessgame?gid=1267516

...on Chessgames.com, where there are lots of comments on the missed opportunities of the two players plus explanations of the drawing maneuvers.