The Borj Nord (North Fort) sits on the hill above Fes el-Bali, built by the Saadian sultan Ahmad al-Mansur in the 1580s to defend the city — and to keep an eye on the unpredictable medina population below. Today it houses the Arms Museum, with a collection of over 8,000 weapons spanning Merinid swords, Ottoman firearms, Spanish cannon, and Moroccan tribal daggers.
The collection is genuinely interesting, but the better reason to come is the view. The fort's terraces give you the most comprehensive panorama of the medina available from anywhere near ground level: the white mass of Fes el-Bali filling the bowl below, green rooftops of Al-Qarawiyyin at the centre, the Ville Nouvelle grid in the distance. Combine with the Merinid Tombs (a short walk along the hillside) for the full elevated circuit.