The Dome of the Spirits is a small octagonal dome located close to the Dome of al-Khidr. It is based on eight marble columns attached to eight arches carrying the dome’s drum. The structure was probably built during the 10th century AD. It is frequented regularly by sufis and is used as a place for making zikr.
References: A guide to al-Aqsa mosque – PASSIA, HUMA’s travel guide to Palestine