Milan, 25 February 2025 – A more direct and convenient transfer between Milan’s M4 and M2 metro lines at Sant’Ambrogio station. This is a newly opened covered pedestrian corridor, built by Webuild, connects the two lines while showcasing medieval artefacts uncovered during construction. Thanks to a glass floor, these discoveries are now displayed as if in a grand exhibition case for the public to admire.

The new corridor cuts transfer times in half, saving the station’s passengers from having to exit to the street level and walk outdoors. This project is part of Webuild’s work for the City of Milan on the M4 metro line. Since its full opening last October, the M4 has allowed around 135,000 passengers per day to cross the city from east to west in just 30 minutes, thanks to its 21 stations and 15 kilometres of track connecting Linate Airport to San Cristoforo station.

The new corridor is a prime example of how modern infrastructure and historical preservation can coexist. Spanning 70 meters in total, the tunnel features a 50-square-meter walkable glass display case that protects and showcases a remarkable archaeological find uncovered during construction: a 35-meter-long wall that once served as a retaining structure for the Naviglio San Gerolamo. The design solution, specifically developed to preserve and highlight the discovered structures, allows passengers to walk along the very "bed" of the medieval canal. Flanked by the original containment wall made of Lombard “ceppo” stone and structures once connected to the Pusterla di Sant’Ambrogio, the corridor offers a unique journey through history.

The preservation of the corridor’s ancient flooring is just one of many initiatives undertaken by Webuild to protect and promote the historical and archaeological heritage uncovered during the construction of the M4 Line. Similar efforts have been carried out in other infrastructure projects led by the Group, both in Italy and worldwide, including Rome’s Metro Line C and the Thessaloniki Metro in Greece. Under the direct supervision of Milan’s Archaeology, Fine Arts, and Landscape Superintendence, Webuild has already restored and returned several historical artifacts to the city. These include a section of the ancient canal wall inside De Amicis station, the Colonna del Verziere and the Statue of the Redeemer in Largo Augusto, and the Ruvida Colonna—discovered during the temporary relocation of the Colonna del Verziere to allow for M4 construction. Other restored landmarks include the Bust of Cesare Correnti in Piazza della Resistenza Partigiana, the medieval wall on Via Francesco Sforza, and the Monument of the Madonna della Rassegnazione.