Vertical Forest is a pair of residential towers in the Porta Nuova district of Milan, Italy, between Via Gaetano de Castillia and Via Federico Confalonieri near Milano Porta Garibaldi railway station. They have a height of 111 m and 76 m and will host more than 900 trees (approximately 550 and 350 trees in the first and second towers respectively) on 8,900 m2 of terraces. Within the complex is also an 11-story office building; its facade does not host plants.
The project was designed as part of the rehabilitation of the historic district of Milan between Via De Castillia and Confalonieri. The name imply that each tower houses trees between three and six meters will help mitigate smog and produce oxygen. It is also used to moderate temperatures in the building in the winter and summer. The plants also attenuate noise. The design was tested in a wind tunnel to ensure the trees would not topple from gusts of wind. Botanists and horticulturalists were consulted by the engineering team to ensure that the structure could bear the load imposed by the plants.The two buildings have 730 trees (480 large, 250 small), 5,000 shrubs, and 11,000 perennials and groundcover on its facades. The original design had specified 1,280 tall plants and 920 short plants encompassing 50 species. Overall, the vegetation is the equivalent of that found in a one hectare woodlot. The innovative use of heat-pump technology is helping to slash heating and cooling costs.