Even before he became Emperor and took the name Caesar Augustus, Octavian decided on the construction of a dynastic tomb. This was in 29 BC, immediately after the conquest of Egypt and the elimination of his strongest enemy, Mark Anthony. Octavian's policies had a Hellenistic bent right from the beginning and this mausoleum provided a confirmation:

he chose to model his dynastic tomb on the most famous sovereign's tomb of the age, the tomb of King Mausolus.
This monument, devastated by centuries of sacking and pillaging, was finally "liberated" by the 1936 excavations, but it was difficult to understand how it was actually constructed. It was circular building of seven concentric masonry rings each connected with the other by radial walls and superimposed on a travertine basement 12 meters high. In front of the entrance, there were two pillars holding bronze plates on which was inscribed the official biography of the Emperor.
This is the same biography that has been found on other important buildings scattered throughout the provinces of the Empire and it was also written on the side of the building that, until recently, housed the Ara Pacis.
The two obelisks that decorated the mausoleum entrance were brought to Rome from Egypt. They were later moved and re-erected, one in Piazza del Quirinale and the other in Piazza dell' Esquilino.