English: Heraldic banner of arms of Trinity College Dublin in overall proportions 3:2 (ref pic). The blazon (used since 1612, (re-)granted in 1901) is, according to the Victorian grant :

Azure, a Bible closed, clasps to the dexter, between in chief, on a dexter a lion passant, on the sinister a harp, all or, and in base a castle with two towers domed, each surmounted by a banner flotant from the sides, argent, the dexter flag charged with a cross, the sinister with a saltire, gules.