Montsalvat is mountain on top of which Percival Schuttenbach found a wonderful Grail made of milky opal. He exchanged it later for a mule.
In the non-canon short story Coś się kończy, coś się zaczyna, Galahad mistakes the ruins of Rozrog for Monsalvat. Geralt and Yennefer's wedding takes place at the ruined castle of Rozrog.