The "Library of Trees", a ten-hectare park opened in 2018 on the last open ground of the Porta Nuova development, designed by the Dutch studio Inside Outside. Rather than a conventional lawn-and-path garden, it is laid out as a grid of circular tree groves — each a different species, labelled like the entries of a catalogue — crossed by straight walking lines and dotted with flower meadows and event spaces.
It is the green counterweight to the glass towers around it, linking Piazza Gae Aulenti, the Bosco Verticale, and the Isola neighbourhood with a continuous public route. There are open-air fitness areas, a dog run, and a regular programme of markets and yoga classes. As the young plantings mature it is slowly becoming a proper park; for now it is a pleasant, distinctly 21st-century place to cut through the district on foot.