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."