Open reservoir, 152 x 152 x 10-11 m. Capacity ca. 250.000 cubic meters. Like the Aetius reservoir, it was built of alternating bands of brick and stone-faced mortared rubble (brick bands: 0,5 m, stone bands, 1.2 m). South-west wall displayed a series of brick arches consisting of two courses of radially-laid bricks about 0,8 m high. Frochheimer and Strzygowski noted a channel running east from the middle of the south-west flank of the reservoir, likely from the Thrace-channel. Unfortunately due to the destruction of the uppermost parts of the walls, and the debris on the lowest levels, in- and output channels are not visible today (Crow et al., 2008, p. 129-130).

Major cisterns like these (Aetius, Aspar) seem to have been built alongside the new high level water supply on purpose (Crow et al., 2008, p. 123).

Hero of Byzantium's Geodesia manuscript still shows the reservoir of Aspar filled with water; it might merely be a convention, or evidence that it was still in use. Repairs in the recessed brick technique at the south corner suggest attention in the 10th century, although it is not certain whether this was because it was in use or whether the area was put to a new purpose such as market gardens (Crow et al., 2008, p. 131-132).

At the end of the 10th century, a cylindrical tower was built in the north corner of the reservoir, presumably to lower the water pressure.

During the 16th century, Süleyman I built a small mosque in the cistern, which had been dry for a long time at that point.

Nowadays, the Reservoir of Aspar hosts a park and a children's school (Çarşamba Çukurbostan Parkı).