During 2004, prior to the construction of a large underground car park in the area occupied by the Basin of Porta Ticinese (for a length of circa 400 m from the confluence of the Naviglio Grande), the Archaeological Superintendency of Lombardy ordered five trenches to be opened on the construction site. These aimed to identify the exact position of the structures relating to the defensive walls dating to the Spanish period which extended along the NE bank of the basin, as well as the archaeological stratigraphy on the site. The trenches were excavated along the eastern side of the basin on viale D’Annunzio and on the floor of the basin which had been drained for the purpose. The excavation, which began in August 2005 and has for the present been interrupted, led to the identification of three distinct historical phases. The earliest phase which pre-dates the Spanish domination, is attested by a wooden floor built on piling which was part of the 15th century “Conca del Naviglio”. The subsequent phase (second half of the 16th century) saw the construction of Milan’s city walls during the Spanish domination. The entire length situated within the project area was identified. The last phase was attested by the structures belonging to the basin dating to the first half of the 19th century. The entire north-eastern face was identified, along the bank beside viale D’Annunzio.