About 12km south of Nungwi, on the main road to/from Zanzibar town, are the ruins at Fukuchani and Mvuleni. These are the remains of large houses dating from the 16th century. They're worth a short stop if you're driving this way, and a possible excursion from Nungwi if lying on the beach gets all too much.
Fukuchani ruins (Tufuku 5º49.365's; 39º17.479'e) are on the edge of the village of the same name. Beside a large school on the western side of the road, there's a small signpost under a baobab tree which will point you in the right direction, along a track that bisects the local football pitch. The ruin is known locally as the 'Portuguese House', but although some Portuguese settlers may have built houses on Zanzibar during this period, this structure is considered by archaeologists to be of Swahili and not foreign origin. The ruins are well maintained and the surrounding land has been mostly cleared of vegetation.
Built in the 16th century, Fukuchani is a fortified dwelling that may have belonged to a wealthy merchant or farmer. It is constructed of coral bricks, with arched doorways and rectangular niches in the walls of the main room, and surrounded by a stone wall in which small holes have been inserted. It has been suggested that these are gun slits for the purposes of defence, but a more recent theory suggests they may have been to hold projecting beams which supported a raised walkway, so that anyone inside the enclosure could see over the wall. The ruins are in good condition, compared with many others on Zanzibar of a similar age, and quite impressive. Buildings of a similar style have been found at other sites along the east African coast, though, alongside the ruins at Mvuleni, Fukuchani represents the finest domestic stone house architecture of this period.
Behind the ruin, a path leads to a small beach. Across the channel you can see Tumbatu Island, with the lighthouse at its northern tip clearly visible. At the southern end of the island are the remains of a large town, dating from around the 12th century (for more details see the Tumbatu Island box above).
Mmvuleni ruins (tumvul 5º49.77's; 39º17.496'e) lie just to the south of Fukuchani, on the other side of the road (east), where you'll see a small signpost. Next to a few huts and a small shop, a path leads through banana and palm plantations to reach the site. Like Fukuchani, this structure was probably once a fortified house that would have belonged to a powerful member of the community. It, too, was thought to be the work of Portuguese invaders until recent research suggested that it is more likely to be Swahili in origin. The house was once larger than the one at Fukuchani, with thicker walls, but the ruins are in poor condition, and are partly overgrown with vegetation, obscuring some of the architectural features. Substantial sections of the walls remain standing, though, complete with carved door arches, conveying something of the impressive building that this once was. One of the most interesting features of this house is the large natural cavern just northeast of the house, outside the main wall. Crystal clear, salt water flows through the cave, collecting in a pool visible beyond an entrance fringed by vegetation: this was probably a source of water when the house was occupied.
Tumbatu is one of the largest of Zanzibar's offshore islands, measuring about 8km long by 2–3km across. The people of the island, the Watumbatu, speak their own dialect of Swahili. They have a reputation for pride and aloofness, and are reputed not to welcome visitors on their island. The Watumbatu men are traditionally known as the best sailors on Zanzibar, or even on the whole east African coast. On the southern end of Tumbatu Island are a group of Shirazi ruins, thought to date from the 12th century. An Arab geographer writing in the 13th century recorded that the Muslim people of Zanzibar Island were attacked (by whom is not clear) and retreated to Tumbatu Island where they were welcomed by the local inhabitants, who were also Muslim, and it is assumed that these people were responsible for the Shirazi ruins. The ruins were probably abandoned in the early 16th century, but the Watumbatu still claim to be descended from Shirazi immigrants.