the exterior walls were first constructed from calp limestone, which were then faced with 22.86 cm (9 inches) of ballyknockan granite. the quoins, columns and 108 capitals, as well as the string course which can be seen halfway up the building, are all of portland stone from the isle of portland, dorset. the tympanum over the heavy wooden main door to building and which bears the crest of the college (a popular 19th-century variant, slightly different from the one currently used by the college today) is of caen stone from caen, france. overall the exterior amounted to just under half the cost for the entire building.