Yes. There are a couple routes he might have learned of it, though:
Slytherin’s monster, as a high-level creature keyed into the deepest wards, might be expected to know of it or be able to learn of it.
If my speculation about the Map’s anomaly is right, Voldemort’s spirit could have learned of it by directly observing the twins.
The Map has been passed down through the ages and sometimes even been in official possession, so it could be mentioned in some obscure book. Possibly it might be a headmaster secret, explaining how Dumbledore learned of it without requiring him to invade their minds.
The twins could have been suspiciously—to Quirrel—adept at avoiding professors and obstacles, prompting him to spy on them as one would expect Quirrel to do.
The Map could be revealed at a future date; Quirrel’s suspiciously good priors have long been speculated as being related to time travel.
None of them seem especially likely, but in aggregate with other strategies I have failed to think of...
Yes. There are a couple routes he might have learned of it, though:
Slytherin’s monster, as a high-level creature keyed into the deepest wards, might be expected to know of it or be able to learn of it.
If my speculation about the Map’s anomaly is right, Voldemort’s spirit could have learned of it by directly observing the twins.
The Map has been passed down through the ages and sometimes even been in official possession, so it could be mentioned in some obscure book. Possibly it might be a headmaster secret, explaining how Dumbledore learned of it without requiring him to invade their minds.
The twins could have been suspiciously—to Quirrel—adept at avoiding professors and obstacles, prompting him to spy on them as one would expect Quirrel to do.
The Map could be revealed at a future date; Quirrel’s suspiciously good priors have long been speculated as being related to time travel.
None of them seem especially likely, but in aggregate with other strategies I have failed to think of...