Possibly the Bonus cistern, it meets the requirements of 'a covered cistern north-east of the Church of the Holy Apostles' (see Crow et al., 2008, p. 128).
Late antique rectangular cistern, 29.1 × 18.7 m, with 26 windows for air circulation and beveled corners (counter water pressure from the inside). The walls are 2.8 m thick; the bricks being 4 cm thick with mortar joints 7 cm thick. The ceiling consists of 40 small brick cross vaults, supported by 28 columns (4 rows of 7). The columns are made of granite (6×) and Proconnsian marble (22×). Its location likely indicates that it was supplied by the Valens Waterway (Hendrix and Altuğ, The Byzantine Legacy). The stairs in this cistern were probably to increase accessibility for maintenance when it was in use (Crow et al., 2008, p. 140).
Possibly the cistern of the palace of the patrician Bonos (d. 627). Romanos I Lekapenos (r. 920-44) reportedly later built a summer residence here. In Ottoman times, the Sivâsî Tekkesi Sufi lodge was built on top of the cistern, until it disappeared in the 19th century. In the 19th century, it was used by Armenian silk spinners, and abandoned in 1987 until its restoration in 2007.
Nowadays, it is a wedding and event venue.
