Complex sentence: It stands three storeys in height and has a stair-tower extruded on the NW; the masonry is of lime-mortared random rubble and is readily distinguished from its 19th-century ashlar superstructure.
Split into simpler sentences: It stands three storeys in height and has a stair-tower extruded on the north west. The masonry is of lime-mortared random rubble and is readily distinguished from its 19th-century ashlar superstructure.