The Ustrinum of Antoninus Pius , in the centre of the picture, had a great column, Antonine Column, that you can notice in the foreground of the enclosure. The Ustrinum itself was consisting of three concentric square enclosures. The Ustrinum of Antoninus might have been built by Antoninus himself, but for Faustina who died in 141. It might then have been used for Antoninus after his death in 161.