The ruins – which are surrounded by rusted barbed wire and set between baobabs overlooking nearby mangroves and coastline – include the crumbling remains of a mosque and about 20 overgrown Shirazi pillar-style tombs, the largest collection of such tombs on the East African coast. Both the mosque and the tombs are estimated to date from the 14th or 15th century, when Tongoni was a major coastal trading port. Although most of the pillars have long since toppled to the ground, you can still see the recessed areas on some where decorative porcelain vases and offering bowls were placed. There are also about two dozen more recent, and largely unremarkable tombs dating from the 18th or 19th century.