The majority of visitors head directly to the Sofa-ı Hümâyûn (Imperial Terrace), also known as the Mermer Sofa (Marble Terrace). This is where most of the impressive pavilions were built by the sultans.
The terrace is partially colonnaded and contains a pool in the center.
Next is the Sünnet Odası (Circumcision Room), in my opinion the most beautiful of the pavilions. It dates back to the time of Süleyman the Magnificent and was renovated by İbrahim in 1640. It was originally intended as the Yazlık Oda (Summer Room), but was referred to as the Circumcision Room after Ahmet III had the circumcisions of his sons performed there.
The Sünnet Odası is richly decorated with stunning tilework inside and out.
A popular photo op for tourists is the İftariye Köşkü (Iftar Kiosk). It was built for Sultan İbrahim as a place to break the fast at sunset during Ramadan. The sultans were also able to watch sporting events in the yard below and see across the Golden Horn.
The fourth and final pavilion on the Sofa-ı Hümâyûn is the Bağdad Köşkü (Baghdad Kiosk). It was built in 1639 by Murat IV to commemorate his successful Baghdad Campaign.
The Bağdad Köşkü is my second favorite pavilion because of the gorgeous tilework and mother of pearl on the interior.
Outside of the Sofa-ı Hümâyûn are a few other buildings of note. Near the Tulip Garden is the Sofa Köşku (Terrace Kiosk), also known as the Merdiven Başı Kasrı (Top of the Stairs Pavilion). It was built by Mehmet IV and was used to watch sporting events in the field below as well as hold meetings.
The building consists of two rooms, the Divanhane (Divan Lounge) and Şerbet Odası (Sherbet Room). It was restored by Ahmet III in 1704 and rebuilt by Mahmut I in 1752.
The small field at the bottom of the stairs under the Sofa Köşku was used for the aforementioned sporting events. The Taş Taht (Stone Throne) was made for Murat IV to watch these events. It sits against the Hekimbaşı Odası (Chamber of the Chief Physician), which was also known as the Baş Lala Kulesi (Tower of the Head Tutor). It was originally built as a watch tower under Mehmet II. The Sultan and all residents of the Harem were treated by doctors under the Chief Physician.
The most recent building on the palace grounds is the Mecidiye Köşkü (Mecidiye Kiosk), built in 1859 by Abdülmecit I as a resting place. After moving to their new palaces at Dolmabahçe and Yıldız, the sultans would stay there on retreats and visits to Topkapı. A restaurant is located next to the kiosk as well as the Esvap Odası (Wardrobe Chamber), built in 1859.
Behind it is the Sofa Camii (Terrace Mosque). This mosque was constructed for the Treasury workers to complete their prayers, along with the other structures ordered by Abdülmecit I in 1859.