The 15th century Swahili town of Songo Mnara (Tanzania) had six mosques—an unusual quantity for a town of only 7 hectares and a population of 500–1000 people. Largescale archaeological investigations of two previously unstudied mosques, and detailed survey of the remaining four structures has suggested a complex pattern of Islamic practice in the town, including a dynamic relationship between mosques and burials, an emerging sense of social difference within the town, and the active signalling of Islamic faith to visitors through the construction of monuments intended to be seen on approach to the town. We commend a holistic approach in which mosques are studied not as isolated structures but as part of a wider urban landscape.