Opened in 1935, the Galleria delle Vittorie (Victory Gallery) was built during Fascist Italy in the style of other shopping arcades in the country at the time. It has sat abandoned since the 1970s. The Galleria has four entrances, each featuring frescoes of some of Italy's "victories," mostly from the First World War and the Ethiopian War. 

The central arcade has fallen into a somewhat decrepit state. However, the outer buildings surrounding the center still house apartments and hotels. It's from these and the locked gates the you can see what must have been a stunning undercover shopping area, with mosaic floors and a glass ceiling. 

There have been various efforts to redevelop the deserted building, but none have come to fruition just yet. 

Update October 2018: You can now enter the main courtyard of the Galleria from Via Maqueda and grab a drink at a cocktail bar located within the courtyard.