Ruins of Kilwa Kisiwani and Ruins of Songo Mnara

They are the remains of a Swahili city-state that controlled the East African gold trade between the eleventh and sixteenth centuries, spread across two islands off Tanzania's southern coast. Kilwa Kisiwani holds the Great Mosque and the Husuni Kubwa palace complex, while Songo Mnara preserves a more coherent townscape. Both were inscribed as a UNESCO World Heritage Site in 1981 and remain largely unrestored. Kilwa Masoko on the mainland is the base, and permits and boats are arranged there rather than on the islands themselves.

It controlled the trade in gold coming out of Sofala in present-day Mozambique, which made it the wealthiest and most powerful of the Swahili city-states. Merchants from Arabia, Persia, India and China traded through its harbour, and its coinage circulated widely. Ibn Battuta visited in 1331 and described it as one of the most beautiful cities in the world. The sites see very few visitors, so you are likely to have the ruins entirely to yourself whichever day you go.

The base is Kilwa Masoko on the mainland, around 320 kilometres south of Dar es Salaam, roughly five to six hours by road on largely surfaced highway. Light aircraft also serve Kilwa Masoko airstrip. From the village, small boats cross to Kilwa Kisiwani in about twenty minutes, and Songo Mnara is a longer trip further south. Allow flexibility in your plans, as the short crossing depends on tide and wind and is occasionally postponed.

Yes to both. Entry permits are issued at the antiquities office in Kilwa Masoko and must be arranged before crossing, and a guide accompanies visits to the islands. Local boat operators handle the crossing and usually coordinate the paperwork. Arrange everything the day before rather than turning up expecting to go the same morning. Kilwa Masoko on the mainland is the base, and permits and boats are arranged there rather than on the islands themselves.

Kilwa Kisiwani takes a half day including the crossing, covering the Great Mosque, Husuni Kubwa and the Portuguese fort at an unhurried pace. Songo Mnara needs most of a second day given the longer boat journey. Two nights in Kilwa Masoko allows both islands comfortably, plus time on the mainland beaches, which are quiet and largely undeveloped. The sites see very few visitors, so you are likely to have the ruins entirely to yourself whichever day you go.

Largely unrestored, and that is much of their appeal. Structures stand among baobabs and coconut palms with the sea on three sides, weathered but substantially intact in places. The site spent some years on the UNESCO list of World Heritage in Danger, and conservation work has continued since. Expect an archaeological site rather than a managed monument with interpretation boards. Allow flexibility in your plans, as the short crossing depends on tide and wind and is occasionally postponed.

For anyone with an interest in Swahili history or in seeing a major world heritage site almost entirely without other visitors, very much so. It is a long drive and infrastructure is basic. Travellers looking primarily for beaches or wildlife will find better value elsewhere, but the ruins themselves have few equals anywhere on the East African coast. Kilwa Masoko on the mainland is the base, and permits and boats are arranged there rather than on the islands themselves.

June to October is the dry season and much the best window, with lower humidity, calmer seas for the crossing and firm ground among the ruins. September and October are particularly good. March to May brings the long rains, when the crossing is less reliable and the sites are muddy with vegetation growing quickly over the stonework. The sites see very few visitors, so you are likely to have the ruins entirely to yourself whichever day you go.