A classic example of Mazzoni's work is the railway station in Trento in the north-eastern Italian Alps, built during 1934-36. Trento had a special significance for the Fascist regime as the capital of the Trentino-Alto Adige (Welschtirol-Sudtirol) region, annexed to Italy from Austria at the Treaty of Versailles after World War I.

Trento's railway station represents Mazzoni's interpretation of the functionalist style typical of the times; the building's continuous windows and dynamic structural lines are said to express Futurist ideas of speed and streamlining. The station stands out due to its innovative use of steel, glass, and several varieties of local stone. The station offers platforms on four rail tracks and its design is intended to facilitate the flow of people from the street to the trains. Wide wood-frame doors open on the entire facade. A wide, shallow staircase leads to the underpassage to the 2nd and 3rd tracks. Spacious waiting space is provided under cover or indoor.

In addition to ticket offices, a tobacconist, a news-stand and baggage store, the station also provided office space for administration, restrooms, a restaurant and bar (today only a bar remains) and conference rooms and meeting space. Mazzoni was more than an architect. He also was an important interior and furniture designer, and all the components of his buildings, from wall decorations to brass door-handles and glazed screens, were designed by his office. The main hall of Trento railway station was decorated with large mosaics depicting the life of the people, and the natural beauties of the mountainous region around Trento. These depictions were typical of the time and served an educational-propagandistic purpose. Originally, the ceiling is said to have been painted light green.