Heading in the other direction from the fountain you'll come to the fortress and Archeological Museum (Tues-Sun 8.30am-3pm; a?¬1.40), which occupies a building almost directly opposite the entrance to the fortress. This was built by the Turks as an extra defence, and later served as a prison, but it's now entirely modern inside: cool, spacious and airy. Unfortunately, the collection is not particularly exciting, and really only worth seeing if you're going to miss the bigger museums elsewhere on the island.

The massive Venetian fortress (Tues-Sun 8am-7pm; reduced hours out of season; a?¬2.40) is a must, however. Said to be the largest Venetian castle ever built, this was a response, in the last quarter of the sixteenth century, to a series of pirate raids (by Barbarossa among others) that had devastated the town. Inside is now a vast open space dotted with the remains of all sorts of barracks, arsenals, officers' houses, earthworks and deep shafts, and at the centre a large domed building that was once a church and later a mosque (complete with a surviving but sadly defaced mihrab ). It was designed to be large enough for the entire population to take shelter within the walls, and you can see that it probably was. Although much is ruined, it remains thoroughly atmospheric, and you can look out from the walls over the town and harbour, or in the other direction along the coast to the west. It's also worth walking around the outside of the fortress, preferably at sunset, to get an impression of its fearsome defences, plus great views along the coast and a pleasant resting point around the far side at the Sunset taverna.