A forest and castle.
Lancelot was six miles from Florega, in the wood of Sapine, when he learned that Meliagrant's stepsister was to be burned at Florega the next day. That night, on his way to Florega, Lancelot stopped at a house of religion where he found Duke Galeholt's tomb.
From this I surmise that Sapine Wood was in or near Duke Galeholt's favorite kingdom of Surluse (Sorelois). The judgment of Meliagrant's sister at Florega suggests a location exactly between Surluse and Gore.