While Stone Town was included in UNESCO's World Heritage Sites in 2000, this designation does not provide complete protection for the town's heritage. Despite the establishment of a Conservation Authority, about 80% of the 1,709 buildings of Stone Town are in a deteriorating condition. As coral stone is very friable, frequent maintenance is needed for most of these buildings. Some major restoration projects (especially on the seafront) have been done in recent times by the Aga Khan Trust for Culture (AKTC).