During April 2009 a trench was excavated in the House of Grand Duke Michael which aimed to clarify the spatial organisation in the rear part of the house during the Samnite phase. In fact, previous campaigns had exposed most of the rooms of the early house and had reconstructed the plan of the atrium and part of what was thought to be a hortus. However, the latest stratigraphic excavations provided unexpected data which showed this was not a simple garden but a porticoed area in the phase datable to the 2nd century B.C. In fact, in this period the early garden was monumentalised by the construction of a portico on at least two sides. This structure constitutes the earliest example of a peristyle built around a mid-level house, whose chronology makes it possible to move back the dating for the beginning of the generalised diffusion of this type of structure in mid-level Pompeian houses, which is normally considered to date to the final years of the 2nd century B.C.

Also of interest was the presence of a room (9a) – with a window opening onto the portico – which extended further towards the back of the main house than did the other rooms accessible from the atrium, according to a typology which finds parallels in other houses of the mid-Samnite period at Pompeii, such as the House of the Orchard and the House of the Scientists.