The Heri es-Swani, or Royal Granaries, are one of the most dramatic ruins in Morocco. Moulay Ismail built these enormous underground storerooms beside the Bassin de l'Agdal to supply his imperial capital. The vaulted chambers stretch for hundreds of metres, and the scale of the construction is staggering — thick walls designed to maintain cool temperatures year-round, a sophisticated ventilation system, and storage capacity for thousands of tonnes of grain.
The ruins are well preserved and freely accessible from the Bassin de l'Agdal. A small entrance fee may be charged at the gate. The atmosphere is unlike anything in the medina — cool, echoing, and genuinely ancient-feeling despite dating from the 17th century.