Three trenches were dug in the area of Piazzale Baracca in order to investigate the archaeological situation prior to the construction of an underground car-park, as it is situated on the line of the Spanish city walls (16th century), as shown on historical maps from 1600 onwards.

Phase I – 16th century: construction of the Spanish defensive walls.

Trench 3 (20 × 3.50m), in the garden west of the piazzale, revealed a tract of the south-western perimeter of the bastion of the curtain wall (16th century). Its position is further to the west than that marked on the cadastral map of the 1800s. The structure runs for 20m in a NW-SE alignment. Along its eastern side, the bastion is abutted at right angles by three buttresses (0.90m wide, distanced at 3.50m); along the west side a length of the curtain wall’s facing was identified (4m long, 3.10m thick). The walls were built in bricks (26 × 12 × 6cm) placed in a fairly regular pattern and bonded with strong white mortar. The curtain wall facing has regular courses of mortar bonded bricks in its upper part, the lower courses are formed by large squared blocks. Along its western side the curtain wall is wider at the base forming a sort of steep downward slope. The structure is 1.50m wide at the top and reaches a width of 2m at the bottom.

Phases II-III – post 16th-20th century: structure falls into disuse, new building activity and the area is turned into a garden.

Trenches 1 ( 16 × 4m) and 2 (5 × 5m), in the garden north of the piazzale, revealed post 19th century walls, floor levels and infrastructures. The lowest layers investigated appear to be just above natural.
In trench 3 the abandonment of the structure is attested by levelling and robbing which obliterated short tracts; the disuse of the ditch by a series of rubble deposits which progressively filled it. Abandonment dates to the 19th century and is contemporary with the construction of a basement structure north-east of the bastion. (Delfina Consonni, Carla Pagani)