The highest terrace is a marble-paved area with a pool in the center embellished with a fountain, around which are arranged the Circumcision Room of the Crown Princes in the harem, the Baghdad and Revan Pavilions, and jutting through them balustrade of the terrace, the baldachin- like open kiosk known as the Iftariye Kameriyesi. As we turn into the fourth court from the Privy Court, -to the left we see the Circumcision Room of which original date is unknown although it is generally accepted as having been built at the beginning of the 16th century. The present structure owes its appearance to the renovations of the reign of Sultan Ibrahim. The single-chambered pavilion, which sports a wing at the rear bears an inscription as 1641. It is decorated with 16th century tile on both the inner and outer facades, which have been re-used throughout. Although generally employed as a venue for the circumcision of crown princes, it was also used by the sultans from time to time.
The Iftariye Kiosk, which graces the terrace between the Circumcision Room and the Baghdad Pavilion, bears the inscription 1640. It consists of an elongated rectangular baldachin on slender columns. This gilded porch was, during summer, the chosen site for the sultan’s vigil during Ramazan-the month of fasting-towards sunset and the end of the daily fast.
The most noticeable structure on this terrace is, however, the Baghdad Pavilion. Octagonal in plan, it has two doors. These doors open up to a single chamber that was used as a coffeehouse for the sultans. Surrounded on the exterior by a portico supported on 22 columns, the pavilion dates from 1639 and owes its existence to the Baghdad Campaign of Murat IV during which it was built. The architect is not known, although it is generally attributed to Kasim Aga, who was the royal architect between 1623- 1651.
A replica of the Baghdad Pavilion in plan but smaller in scale is the Revan Pavilion, which shares the first terrace with its larger counterpart. Built by Murat IV in 1635 to celebrate his Revan Campaign, it was used as the Turban Room or Sarik Odasi. A wooden roofed balcony, the roof supported on spiraelled wooden columns fronting the buildin overlooks the tulip garden.
Leading down from the terrace with a pool to the sofa terrace, also known as the tulip garden, are two flights of steps which give access to the Sofa Pavilion, the Tower of the Chief Physician or Hekimbasi Kulesi, the Mecidiye Pavilion and the Privy Wardrobe or Esvap Odasi.
The Sofa Pavilion, also known as either the Merdivenbasi Kasri or the Pavilion of Mustafa Pasha, is the only wooden pavilion of its kind in the palace According to one account- (the Silahtar Tarihi) a Russian envoy was receive( here in 1682. The earliest inscriptior borne by the actual building however dates from its restoration in 1704, during the reign of Ahmet III.
A second inscription on the facade is found adjacent the tulip garden and gives a second restoration date of 1752 along with the monogram of Mahmut I. The pavilion itself surmounts a wall stretching to the tower of the chief physician at one end and the Baghdad Pavilion at the other. Over the wall are two bays supported on pillars, which betray the existence of the Grand Assembly Hall or Divanhane and a second chamber used for ritual prayer or sherbet ceremonies The assembly hall is decorated by a fine timber ceiling and painted walls in Turkish Rococo.
The nearby Hekimbasi Kulesi, also known as the Tower of the Chief tor of the Imperial Heirs or Baslala Kulesi, is pre-Ottoman in origin, but was incorporated into the palace during the reign of Mehmet the Conqueror. It is a square structure, with walls 1.70-meters thick. It was topped with a conical roof during the 16th century. A chestbelonging to the chief court physician was placed there subsequent to its restoration in 1912. It was used as an armory workshop at one point, and also as a private studio retreat or Meskhane. It is now the palace pharmacy.
From the tower, we may reach the lowest terrace of the fourth court via a flight of steps that lead to the Mecidiye Pavilion, the Esvap Odasi and the Sofa Mosque, buildings of differing eras, Although the exact date of construction is not known, both the Mecidiye Pavilion and the Privy Wardrobe or Esvap Odasi were built during the reign of Abdulmecid ( 1839-1861) and reflect prevalent western architectural style. The nearby Sofa Mosque bears the date 1859 in an inscription, and it is thought that the pavilions were built about that date, when the mosque was also redecorated to match the contemporary style. The Mecidiye Pavilion replaced two earlier buildings, the Cadir Pavilion and the Pavilion of the Third Court, and was used as a reception hall for visiting heads of state. The upper floor is still employed for this purpose.
The Mecidiye Pavilion was not actually constructed until Topkapi Palace ceased to be the seat of the Ottoman sultans, when the remainder of the palace was left to retired servants, and in its decay served as a shelter for the destitute and disabled. It was not until after the foundation of the Republic of Turkey that it was turned into a museum, in 1924.