North of Oristano, a brief bus ride from the rail and road junction of Macomer takes you to BOSA and the coast. Stranded in the middle of one of Sardinia's last remaining stretches of deserted coastline, and so far overlooked by the tourist industry, the town huddles on the banks of the Temo river around a hilltop castle. From the riverside the corridor-like streets of the old district, Sa Costa , ascend the contours of the hillside, full of medieval gloom. To explore these backstreets, take any road leading up from the Cathedral , on the northern side of Bosa's main bridge. Keep climbing for about twenty minutes to reach Bosa's Castle (summer daily 10am-noon & 4-7pm; erratic hours in winter; free), erected by the Malaspina family in 1122 - there's also a road that skirts the back of town, leading round to the castle gate. From the castle ramparts you can pick out the ex-cathedral of San Pietro , an eleventh-century construction with a lovely Gothic facade added by Cistercian monks a couple of hundred years later. From the bridge, it's a two-kilometre walk along the river to the church.

In the other direction, BOSA MARINA lies 5km downstream on what was the town's original site before its inhabitants shifted to a more defensible position. Today it is a conventional minor resort with a small choice of hotels and trattorias, its tiny port and beach in the lee of the islet of Isola Rossa, now linked to the mainland and guarded by an old Spanish watchtower.