The archaeological investigation covered an area of circa two hectares and examined the Mausoleum of Augustus, the immediately surrounding area and, to a certain width and depth, the area beyond. The investigations were undertaken due to the necessity of determining the feasibility of a project to modernise the whole of piazza Augusto Imperatore.

The trenches opened in the circle surrounding the mausoleum revealed, at between 30 and 40 metres to the east and west of the entrance to the tomb, the position of the opus caementicium foundations of two obelisks which in antiquity flanked the monument. The obelisk situated to the east still preserved part of the core of its base.

In the central zone the modern flight of steps which provided access to the area was demolished and an intermediate level of graves and “a cappuccina” tombs, the post abandonment levels and further ancient levels were removed. This exposed a stretch of paving in travertine slabs, positioned at a level of 10.58 m a.s.l., which can be linked to the large stretch of paving situated on the side of the access stair way and discovered in the 1950s; this was already visible before the beginning of the excavations.

The investigations in the southern sector of the area revealed the remains of the ground floor and basement levels of the Renaissance building which housed the ‘Collegio dei Croati’ which was demolished between 1934 and 1936. The demolition of the buildings revealed Renaissance structures in direct contact with Roman levels and, in particular, with an ancient surface formed of carefully worked travertine blocks and a cement foundation. The presence of the foundation, of lines and crosses incised on the blocks suggests the existence of standing structures that have not survived.

North of the mausoleum between via di Ripetta and via dei Pontefici the excavation of the remains of Palazzo Sonderini exposed, in continuity with the Renaissance structures, walls belonging to a building of 1st-2nd century date, the so-called domus del curator Augusti.

The investigations on the monument undertaken by Colini in 1925-26 and again in 1936-39 were anything but exhaustive, and thus the cavities and trenches dug at that time were reopened and the investigation extended to the entire research area. In particular the investigations inside the mausoleum looked at the annular ambulatories around the cella revealing the foundations of the walls in travertine blocks and the collapse of the annular vaults covering the ambulatories which were also entirely built in blocks.

Of the opus reticulatum substructures between the third and fifth ring, not practicable in antiquity, the first of the semicircular concamerations to the east of the dromos was partially excavated. A complete investigation was made of the eastern sector of the second concameration where the original Augustan fill was seen to reach the Renaissance level of reuse of the area. The investigation has shown that the opus reticulatum walls were built without scaffolding but by creating a series of platforms by dumping earth inside the concamerations.