There was an early attempt at symmetry in the external appearance of the great hall – the Strong and Saintlowe Towers architecturally act as near symmetrical "wings" to the hall itself, while the plinth of the hall is designed to mirror that of the great tower opposite it.[20] An unusual multi-sided tower, the Oriel, provides a counterpoint to the main doorway of the hall and was intended for private entertainment by Gaunt away from the main festivities on major occasions.[21] The Oriel tower is based on Edward III's "La Rose" Tower at Windsor, which had a similar function.[22] Gaunt's Strong Tower is so named for being entirely vaulted in stone across all its floors, an unusual and robust design.[23] The great hall influenced the design of Bolton and Raby castles. The hall's roof design was independently famous and was copied at Arundel Castle and Westminster Hall.[24]