Modern Description:
On the top of the long ridge of mountain west of Aghios Sostis, appositely called ‘Selladi' (‘saddle'), are the remains of an ancient fortress-acropolis, marked today by the church of Aghios Nikitas. (A small, easily missed sign indicates the path up from the main road, from a point just west of the church of Aghios Ioannis (at 4.7 km), which lies in the floor of the valley to the south of the road, midway along. Allow at least 50 minutes each way.) This is the first of two such fortified, highly panoramic points to either side of this valley: the other is at Prophítis Elías Troulakíou, clearly visible from here to the southeast. Visibility between the two was obviously important. Aghios Nikitas guards the northern and eastern approaches to the island; Prophitis Elias, those from the west. Both sites are marked by a dense quantity of fallen, limestone masonry. Neither was an ‘acropolis' in the sense of a large, habitable place of refuge, but rather a fortified complex of buildings for the security of the land and operations around. The humble church of Aghios Nikitas, itself constructed with ancient stones, sits at the southeastern corner of an easily discernible rectangular terrace built, bordered and cornered in ancient masonry which would appear to date from the Late Archaic period. Finds from Mycenaean times in this area, however, suggest a considerably earlier presence on this spot. The massive blocks of the walls of a structure still remain to the north of the hut which stands beside the church, and quantities of fallen and broken blocks lie on all sides. A date in the late 6th century BC for these structures would coincide with the period of maximum exploitation of the silver mines at Aghios Sostis.
Info: McGilchrist's Greek Islands 
(From McGilchrist’s Greek Islands, © Nigel McGilchrist 2010, excerpted with his gracious permission. Click for the books)
