The Sun Temple of Heliopolis is the largest ancient Egyptian sacred precinct. Its significance is based on the assumption that the world was created on this spot. Over a vast timeframe of 2,400 years, rulers’ interests were documented, before the investments suddenly stop in the third century B.C. in as yet unclarified circumstances, following which the temple’s monuments were transported away. During the course of an emergency excavation in area 232, two layers of construction from the 4th to the 2nd century B.C.E. were identified and documented in 2017. The results achieved here show that for this critical period in the temple’s history, findings representative of the process and circumstances of the secularization centuries before Egypt was Christianized can be obtained over an extended area. The results of the research project thus concern firstly the circumstances of the secularization and the inventory before the turning point, and secondly the sequential events in what was once the most important temple in Egypt during the period from the first removals of its monuments, following which, for example, the obelisks were taken to Alexandria and then in the early imperial period to Rome.