The Eski Imaret Mosque (Turkish: Eski Imaret Camii) is a former Byzantine church converted into a mosque by the Ottomans. The church has traditionally been identified as belonging to the Monastery of Christ Pantepoptes (Greek: Μονή του Χριστού Παντεπόπτη), meaning "Christ the all-seeing". It is the only documented 11th-century church in Istanbul which survives intact, and represents a key monument of middle Byzantine architecture. Despite that, it remains among the least studied buildings in the city.

The building lies in Istanbul, in the district of Fatih, in the neighbourhood of Zeyrek, one of the poorest areas inside the old walled city. It is less than one kilometre northwest of the even more impressive Zeyrek Mosque.

It was the Patriarch Constantius I (1830–1834) who identified the Eski Imaret Mosque as the old Pantepoptes church. Although this identification has been generally accepted, Cyril Mango argued that its location didn't allow a complete overview of the Golden Horn, and instead suggested the site currently occupied by the Yavuz Sultan Selim Mosque as an alternative placing for the Pantepoptes Monastery. Austay-Effenberger and Effenberger agreed with Mango, and argued that it might actually have been the Church of St. Constantine, founded by the Empress Theophano in the early 10th century, highlighting its similarities to the contemporaneous Lips Monastery.

Some time before 1087, Anna Dalassena, mother of the Byzantine Emperor Alexius I Comnenus, built a convent dedicated to Christos Pantepoptes on the summit of the fourth of Constantinople's seven hills where she retired at the end of her life, following Imperial custom. The convent included a church, also dedicated to the Pantepoptes.

On April 12, 1204, during the siege of Constantinople, Emperor Alexios V Doukas Mourtzouphlos established his headquarters near the monastery. From this vantage point he could watch the Venetian fleet under the command of Doge Enrico Dandolo deploying between the monastery of the Euergetes and the church of St. Mary of the Blachernae before attacking the city. After the successful attack he took flight abandoning his purple tent on the spot, thus allowing Baldwin of Flanders to spend his victory night inside it. The complex was sacked by the Crusaders, and afterwards it was assigned to Benedictine monks from San Giorgio Maggiore in Rome. During the Latin occupation of Constantinople (1204–1261) the building became a Roman Catholic church.

Immediately after the Ottoman conquest of Constantinople in 1453, the church became a mosque, while the monastic buildings were used as a zaviye, medrese and imaret for the nearby Fatih Mosque, which was then under construction. The Turkish name for the mosque ("Old Soup Kitchen Mosque") recall this.

The complex has been ravaged by fire several times, and the last traces of the monastery disappeared about a century ago. Until 1970 the building was used as a Koran school, which rendered it largely inaccessible for architectural study. In 1970, the mosque was partially closed off and restored by the Turkish architect Fikret Çuhadaroğlu.

It has been restored twice: once in the 1970s by architect Fikret Çuhadaroglu; and again during an unauthorized restoration in the 1990s.