[Illustration: FIG. 159. PLAN OF STE TRINITÉ.] The original exterior (Figs. 160 and 161) is extremely plain, the quoins and doorway with its square lintel being constructed with large stones, probably derived from a Roman building (Fig. 162). The upper part of the walls was raised by the Spaniards, in the sixteenth century, to form a platform for guns. The earlier form of the western gable is visible in Fig. 160. We have evidently, in this primitive structure, a rude attempt to imitate the triapsal and domical forms originally used in the early Christian architecture of the cemeteries at Rome, and afterwards more fully developed in the East. Viollet-le-Duc attributes its erection to the seventh or eighth century. [Illustration: FIG. 160. WEST END OF STE TRINITÉ.] Of the seven chapels which once extended round the island, and formed the object of many pilgrimages, those of Ste Trinité (just described), and St Sauveur near the centre of the north side, alone survive. The latter (Fig. 163) is octagonal on plan, with niches on each of the sides, and a larger central one, forming an apse opposite the door. This apse alone is visible on the outside. The chapel is unfortunately greatly modernised. In course of time the monastery naturally became rich, and formed a tempting bait to the Corsairs of the Mediterranean, whether Saracen or Christian, who attacked and plundered it several times. It is said that on the occasion of one of these descents in 725 St Porchaire and five hundred monks were massacred. A restored chapel to the south of the convent still bears the name of that martyr. [Illustration: FIG. 161. STE TRINITÉ, EAST END.] To provide a safe place of retreat in case of similar attacks in future it was resolved to erect a keep or castle on a promontory of rock which juts out into the sea at the south side of the island. Here a perpetual look-out could be kept over the sea from the watch-tower on the summit, and notice of danger given by ringing the bell (the belfry for which still exists) in time to enable the monks to take refuge with their valuables within the keep. The castle is stated to have been begun about 1073 by the Abbé Aldebert II., partly on Roman substructions and partly on the rock, and the chapel was consecrated in 1088 (_see_ “Les Iles de Lérins,” by the Abbé Allier.) In fifteen years the second floor was commenced, and in 1190 the tower was finished. Having been frequently sacked and destroyed there is some difficulty in making out the original plan. Besides, containing as it does, an open cloister, it differs so greatly otherwise [Illustration: FIG. 162. DOORWAY, STE TRINITÉ.] [Illustration: FIG. 163. ST SAUVEUR, LÉRINS (_from Révoil_).]