Even though being one of the most iconic places of Milano, the square in front of Castello Sforzesco has accommodated for years a traffic congested four lanes road. A narrow Romantic garden, fragmented by a multitude of tarmac paths separates the road from the castle’s moat. Despite the castle sits in the center of a hemicycle, the view towards it is nowadays obstructed by big scale shrubs. In contrast to the brief, the project suggests the expansion of the pedestrian area to the whole hemicycle that surrounds the castle - a circular urban structure that connects Piazza Castello to Parco Sempione – instead of limiting it to the surface which faces the castle’s main façade. In continuation with the Foro Bonaparte project by Giovanni Antolini (1801), which works on the monumental character of the void, and with the study by Giuseppe Piermarini (1814), which proposes a green infrastructure in which the trees defines urban rooms, our proposal considers the area around the castle as a unique continuous system, whose borders are defined by curved green lines of trees. Their trunks, which are positioned following a regular rhythm, performs as the columns of an urban arcade. The packed-earth floor of Parco Sempione is extended to Piazza Castello, while the XIX century flowerbeds are unified into a unique surface of grass, adapting to the irregular topography of the site and linking the higher level of the castle to the lower one of the semicircle. The park enclosure is then pushed back in order to reposition the Castle at the center of the new urban void. As a compensation room, the new square creates the space of transition between the urban and the natural landscape, allowing – once again – the proper distance around the Castle.