Arkham is a fictional town situated in Massachusetts, somewhere north of Boston, probably in Essex County. Created by weird fiction author H P Lovecraft, Arkham is featured in many of his stories. - AsNotedIn

My mental picture of Arkham is of a town something like Salem in atmosphere & style of houses, but more hilly (Salem is flat except for Gallows Hill, which is outside the town proper) & with a college (which Salem hasn't). The street layout is nothing like Salem's. As to the location of Arkham - I fancy I place the town & the imaginary Miskatonic somewhere north of Salem - perhaps near Manchester. My idea of the place is slightly in from the sea, but with a deep water channel making it a port.