Silla
SILLA (sĭl'a, Heb. sillā’, embankment). An unknown place in the valley below Beth Millo (2Kgs.12.20).
SILLA sĭl’ ə (סִלָּֽא). A place of indefinite location cited in connection with the murder of King Joash (2 Kings 12:20). Its association with Millo suggests that it may have been a sector of Jerusalem or a place within its environs.
International Standard Bible Encyclopedia (1915)
Joash was assassinated by his servants "at the house of Millo, on the way that goeth down to Silla" (2Ki 12:20). Wherever Beth-millo stood, Silla was evidently in the valley below it; but nothing is known of what it was or where it stood.