Also called "the Cold Cistern of Anastasius" (Crow et al., p. 128).

The curved end of the Hippodrome, situated alongside the Hadrian line (Crow et al., 2008, p. 117, 128). Later converted into a cistern. According to Altuğ, 2013, p. 24, the walls of the Sphendone were built during Septimius Severus, but the transformation into a cistern happened in the Byzantine period. In the time of Forchheimer and Strzygowski (1893), the Janissary Museum stood on top of the Sphendone, and the key was kept by the bath-attendants of a bath nearby. Today, the Sultanahmet Endüstri Meslek Lisesi is built on top of the Sphendone.

This cistern probably also supplied a classical Ottoman fountain adjacent to Sphendone; furthermore, it may also be related to the Nakilbent cistern (Altuğ, 2013, p. 230-231).

Archaeological evidence

The diameter of the Sphendone is 141 meters, but the cistern occupies approximately 3/5 of the corridor (Janin, 1964, p. 212).

The semicircle structure consists of pure brick in the lower parts, and layered masonry in the upper parts, supported by two rows of relieving arches which contain windows at the top. The wall of the Sphendone is approximately 2.75 m thick; the second (parallel) wall (of 2.70m thick) is connected to the first wall by a barrel vault and flying bettresses (1,5 m wide, intervals of 2,10 m). The second wall is 1,20 wide at the top and 1,95 m wide at the bottom, which lead to trapezoidal barrel-vaulted tanks of 7,75 m × 3,50 m chambers (Forchheimer & Strzygowski, 1893, p. 105).

The water-holding section of the cistern is accessed by a staircase, which was added later. Inside and to the left of the current entrance of the cistern (where?), there is a barrel vaulted passage of approximately 500 m, extending towards the spina of the Hippodrome. Today, this passage has no plaster on its walls, although plastering the interior used to be the method to convert buidings into cisterns in the Byzantine period (Altuğ, 2013, p. 24-25). There are plastered rectangular rooms within the cistern. The cistern walls are approximately 2,75 m thick. Due to the walls, no columns were needed within the cistern to support the structure (Altuğ, 2013, p. 230-231).

Literary evidence

The origins of the cistern in the Sphendone are mentioned in the Patria (10th century) and history of Cedrenus (11th century).

Cistern concordance "Sphedone cistern (F8/5)" in Crow et al., 2008, p. 152: Casson 1928 p. 16-18, figs 19-22; Forchheimer and Strzygowski 1893: p. 104-5 no. 33; Guilland 1969, I p. 376, 442; Janin 1964, p. 211-12 no. 17; Kleiss 1965a, no. 61 on map (duplicated number); Mamboury 1925 p. 481; Mamboury 1936a p. 242-3; Mamboury and Wiegand 1934 p. 40-2; Schneider 1936 p. 89 plan F8; Tonguç 1990 p. 28-9. See also "Çizelge A.45: Hippodrom Sarnıcı" (Altuğ, 2013, p. 230-231).

EDITORS: the map drawing needs to be updated, since the cistern does not cover the entire semi-circular construction.