This extraordinary monument was erected by the Senate to commemorate Augustus' victories in Gaul and Spain, which, according to them, brough the peace of Augustus to the Empire. We know the Gauls (at least) didn't think so - look at the evidence of
Asterix
The monument itself is like a huge, castled throne, with ornately carved marble all around it. The throne itself places the emperor higher than all those around him, and the carvings are heavy with symbolism. The figures carved into several faces depict the imperial family in great detail, together with other senior figures from the senate. These marble processions are interspersed with key legends in the Roman narrative: the killing of the sow by Aeneas, the suckling of Romulus and Remus and other indications of the god-blessed imperium. The carving is exquisite and the faces resonate today.
The building originally sat at the other end of the Campus Martius from the enormous pile of the imperial mausoleum. A huge column, now on the north side of St Giovanni Lateran stood between them and the suggestion is now that it acted as a sun-dial, pointing at midsummer directly at this statement of successful ambition. A table top display gives the approximate positions, and also illustrates the scale of this massive training and parade ground.
The building suffered from the flooding and high water table then endemic in the area, and eventually was excavated and moved to the present site under Mussolini. The building in which it stands, a stark grey box with many windows, is very unlovely from the outside. From the inside it works absolutely brilliantly to showcase this extraordinary monument.
The exhibition hall also brings together copies of the many heads of the family, including those of Augustus and his long-serving and much beloved third wife, Livia. The head of Augustus, of which the original is the in the Capitolini, is a sensitive, pensive face for a man who made such a difference to history.
The mausoleum, long denuded of its illustrious ashes, is the big, green-covered circle outside the polished glass. It is closed to visitors and stands as a mournful block in the streets, too big and clumsy to renew, and to potent to destroy.