When entering the Bâbüssaâde, there is the Enderun Library, behind the Supply Room, opposite. The third courtyard, where the wards of the Enderunites were opened, was therefore called Enderun Square. The Supply Room, which was built during the reign of Sultan Mehmed the Conqueror, was later renovated many times and today the main pedestal part is XV. It is thought to have remained from the century. Like the Justice Tower, which is placed behind the Divanhan, the Supply Room is related to the elevation of the sovereign’s position in the state together with the Conqueror, the enactment and expansion of the powers of the vizier and the Divan-i Hümâyun. As a matter of fact, in the Leysîzâde Kanunname dictated by the Fâtih, it was stated that the Supply Room was mentioned and some issues discussed in the council should be given to the authority of the vizier.
One door of the Supply Room opens to Bâbüssaâde and the other door to the Enderun Square (Enderun Library), which belongs to the ruler. Around the building, there is a promenade with marble colonnaded porches under the eaved roof. There is a throne, a hearth and a fountain inside. When the meeting was held every day in the council, when the meeting was held four or four days a week, the statesmen would meet with the sultan in the Supply Room two days a week, this was called “making the offer”. According to the order determined in the Ottoman state initiation, the janissary chief entered, talked about the issues related to the army, but if there was a vizier, he would wait on the right side of the Bâbüssaâde. Later, accompanied by the sergeant and the janitors, the custodians would go into supply and report issues and decisions regarding education and judiciary. The viziers, sergeant chief and janitors, who were waiting in the council, would break up in the Supply Room with the consultancy of the chamberlain. If the treasurers and marksman had viziers, they would meet with the viziers, if not, they would not. Apart from the offerings made during the days of the Court, the sultan would accept the statesmen whenever he wanted. During the Arafah ceremony, the throne is brought forward to the Bâbüssaâde side of this room, the ruler would have attended the ceremony here (see ROOM OF SUPPLY). Behind the Supply Room, the Enderun Library has been handled extraordinarily, it has a plan with a dome in the middle, three iwans, and is decorated with tiles. There is a large fountain under the stairway. Another building in the courtyard is the Ağalar Mosque. The mosque used by the Enderunlu aghas has another door connected to the harem side. Today, the building is used as the manuscript library of the Topkapı Palace Museum (see AĞALAR MOSQUE). In Enderun, located in the third courtyard, there are large and small rooms, falcons dormitory (hawkins), expeditionary hearth, cellar room, treasure room and Special Room (Department of Sacred Relics). When you entered the Bâbüssaâde, there were the wards of the rooms on the right and left, and the treasure section known as Fâtih Köşkü on the upper right side. In the upper left corner, the stone building with four domes leaning on the Harem section was the Has Room. This place was mostly called Hırka-i Saâdet Dairesi, after the holy relics were brought during the reign of Yavuz Sultan Selim. The main duty of the members of the Has Room, which was established during the reign of Sultan Mehmed the Conqueror, was to protect this flat (see MUKADDES ENTITLEMENT DEPARTMENT).