The Well of Souls (Arabic: بئر الأرواح‎ Bir al-Arwah; sometimes translated Pit of Souls, Cave of Spirits, or Well of Spirits in Islam), also known in Christianity and Judaism by the time of the Crusades as the Holy of Holies,[1] is a partly natural, partly man-made cave located inside the Foundation Stone under the Dome of the Rock shrine in Jerusalem.[2] The name "Well of Souls" derives from a medieval Islamic legend that at this place the spirits of the dead can be heard awaiting Judgment Day.[3] The name has also been applied to a depression in the floor of this cave and a hypothetical chamber that may exist beneath it.[4]