One of the best preserved Kasbahs. It has been declared a World Heritage Site by UNESCO. Very picturesque place, lots of movies were shot there (Gladiator). 10 dirham to visit kasbahs. You don't need a guide, but locals will follow you pretending to help and at the end will ask for money. See more information in the specific article. Be careful not to get too wet from the river when crossing it, since there's been reports of schistosomiasis contracted from the water.