After an expansion during the reign of the Umayyad caliph Al-Walid I, it now incorporates the final resting place of Muhammad and the first two Rashidun caliphs Abu Bakr and Umar. One of the most notable features of the site is the Green Dome in the south-east corner of the mosque, originally Aisha's house, where the tomb of Muhammad is located. Many pilgrims who perform the Hajj also go to Madinah to visit (Ziyarah) the Green Dome. In 1909, under the reign of Ottoman Sultan Abdul Hamid II, it became the first place in the Arabian Peninsula to be provided with electrical lights. The mosque is under the control of the Custodian of the Two Holy Mosques. The mosque is located at the heart of Madinah and is a major pilgrimage site.