Merlin's Mount is in the grounds of of Marlborough College, which is on the eastern end of High Street. "Marlborough" could possibly be derived from the name "Merlin"; Marlborough latinized is Merleburgia.
This is evident in this line from a poem by Alexander Neckham written in 1215: "Merlin's tumulus gave your name, Merleburgia"
However this connection is probably wrong, since the name "Merlin" was "Myrddin" until Geoffrey of Monmouth wrote in 1130-40. Coins have been found from the days of William the Conqueror, which were decades before Geoffrey wrote his stories, where the name of the town is spelled "Maerlebi."
Southern England Arthurian Sites