"During this same period, Constantine built a number of churches. In them, he departed entirely from the architectural style of the pagan temple, evolving instead a new form of the Roman secular building, the basilica - a not inappropriate choice since Church was now equated with State. [...] Of the churches, the first was that of Hagia Irene, the Holy Peace. It stood on the same spot that a temple of Aphrodite had once occupied - a spot occupied today by a sixth-century Byzantine structure. The adjoining site was designated for the first church of Hagia Sophia, the Holy Wisdom, planned by Constantine but built by his son and successor, Constantius II."
The Hagia Irene Church.