Yusuf Agha, a governor of Jerusalem during the reign of the Ottoman Sultan Mehmet IV, built this dome to the west of Masjid al-Qibly in 1681 CE (1092 AH). It is a square-shaped building topped with a small dome. Today, it is used as an information office of Al-Aqsa Mosque.
References: A guide to al-Aqsa mosque – PASSIA