The so-called “Tower of Eirene” (Turkish Eirene Kulesi) is located on the northeastern corner of Büyük Valide Han on Çakmakçılar Slope south of Eminönü. The tower is a square tower measuring over 10m², with a height of approximately 17 m. It currently has three floors made of reinforced concrete, perhaps obscuring evidence of its original floors. Part of its original staircase is located on the second floor within its western wall. French traveler Pierre Gilles is the first to mention the tower, which he refers to it as the “Tower of Eirene” in the 16th century.
The masonry of the tower suggests it dates to the Middle Byzantine era, though it is difficult to determine its history and original function due a lack of clear references in the historical record. It is located around 500 meters from the shore of the Golden Horn, where it had an imposing position overlooking the Neorion Harbor. A 16th century depiction of the tower by Melchior Lorichs suggests it was originally much taller; even now its dominating position suggests the possibility that it was built to function as a watch tower. The tower is commonly associated with Bigla mentioned by Anna Komnene in reference to Venetian concessions. While the name Bigla (βίγλα “watch”) does suggest it was a watch tower, there are no literary references of a tower being associated with this name. The name has also been controversially associated with the commander of the imperial guard (Drungarios tes Biglas). Others have proposed it was part of a Middle Byzantine palace associated with Botaneiates, Kalamanos, or even Romanos I Lekapenos before he became emperor. 
It is possible that the tower was later incorporated into the palace of Lukas Notaras, which is depicted on a version of the map made by Cristoforo Buondelmonti around 1422. Lukas Notaras held the office of Megas Dux and took part in the defense of Constantinople when it was conquered in 1453. It has also been suggested that Eirene refers to the wife of Loukas Notaras, though the name of his wife is uncertain. If it did function as a tower for the palace of Lukas Notaras, then it would have shared features with the aristocratic towers in several Italian cities, including Bologna. Just as in Italian cities, fortified palace towers in Constantinople would have protected leading figures of the city during civil wars. The remains of other fortified palaces in modern Istanbul include Tekfur Sarayı (Palace of the Porphyrogenitus) and probably Mermerkule (“Marble Tower”).
Evidence suggests that it was part of the Cerrah Mehmet Pasha Palace in the 16th century. Later the tower was incorporated into Büyük Valide Han, which was built Murad IV (1632-1640) for his mother Valide Kösem Sultan. It is possible that she used the tower as its treasury. The ribbed doomed roof of the tower also could have been added at the time. There are traces of floral ornamentation dating to 17th or 18th century. It is now part of a panoramic view that the rooftop of Büyük Valide Han provides.