Library of Trees park, Urban park in Porta Nuova district, Milan, Italy.

The Biblioteca degli Alberi park covers 9 hectares between Piazza Gae Aulenti, via Melchiorre Gioia, via De Castillia and via Sassetti in Milan's Porta Nuova district. It holds 500 trees of more than 100 species arranged in 22 rings, plus 135,000 plants, a pond, a hedge maze and a fountain running from May to September.

The park's design was chosen on 20 July 2004 in the international competition for the Giardini di Porta Nuova, won by the Inside-Outside studio with the project "La biblioteca degli alberi". The park, designed by Dutch landscape designer Petra Blaisse and Piet Oudolf with Inside-Outside, was inaugurated on 27 October 2018 at a cost of about 14 million euros.

The park is named for its vegetation: over 100 species, 500 trees in 22 rings and 135,000 plants, arranged like volumes on shelves. Poetic phrases run along the paths, and the park hosts a playground, fitness area, wooden chaise longues, picnic benches and a shrub labyrinth.

The park is bounded by Piazza Gae Aulenti, Via Melchiorre Gioia, Via De Castillia and Via Sassetti, in the Porta Nuova district. Paths run between the 22 tree rings, and the scenic fountain operates from May to September. Benches are set in the picnic areas, and wooden chaise longues stand in the rest area.

The park is laid out as a "library" of vegetation: over 100 species, 500 trees planted in 22 rings and 135,000 plants, a scheme by Dutch landscape designer Petra Blaisse with Piet Oudolf and studio Inside-Outside. The design won the 2004 international competition for the Giardini di Porta Nuova and cost about 14 million euros.