The site was first occupied in the early 14th century but the first mosque; the Great Mosque was not built until AD 1425. Enlargements were undertaken soon thereafter, followed by major reconstruction efforts later in the 15th century following the collapse of the earlier building.
Close to the first Mosque is a smaller mosque which, prior to its construction a much similar but smaller mosque existed at its location; the foundation of its Mihrab may still be seen east of the present Mihrab. The original mosque was built around 1475, while the later mosque in about 1500; this is evident by the presence of a Portuguese dish in the cistern thus indicating that the final alterations to the mosques were probably not completed before the 16th century.
Mnarani was eventually destroyed by the Galla in the early 17th century and archaeological evidence seems to confirm this (Source: National Museums Of Kenya).
To visit the site, or learn more about it, visit the official website.