Umar, the second of the initial four Rashidun Caliphs, was the first conqueror of Jerusalem to enter the city on foot, and when visiting the site that now houses the Haram al-Sharif, A popular account from later centuries is that the Rashidun Caliph Umar was led to the place reluctantly by the Christian patriarch Sophronius. He found it covered with rubbish, but the sacred Rock was found with the help of a converted Jew, Ka'b al-Ahbar. Al-Ahbar advised Umar to build a mosque to the north of the rock, so that worshippers would face both the rock and Mecca, but instead Umar chose to build it to the south of the rock. It became known as the Al-Aqsa Mosque. The first known eyewitness testimony is that of the pilgrim Arculf who visited about 670. According to Arculf's account as recorded by Adomnán, he saw a rectangular wooden house of prayer built over some ruins, large enough to hold 3,000 people. Cities that accepted the new rulers, as recorded in registrars from the time, were: Jerusalem, Nablus, Jenin, Acre, Tiberias, Bisan, Caesarea, Lajjun, Lydd, Jaffa, Imwas, Beit Jibrin, Gaza, Rafah, Hebron, Yubna, Haifa, Safed and Ashkelon.