PLEASE READ - Let me what I went through to identify this building. First of all, we're on the bus on our way to the Trevi Fountain. Only this part of the building can be photographed when I see it. I just raised my camera and focused and squeezed. So what is it? Where is it? I needed to know both answers. Have you noticed the VIEW MAP next to the city& country? Click on it. I geotag each photo. A name or a sign helps, but not in this instance. I looked at my photos before this photo and after it. It was somewhere between the Vatican and the Colosseum. I went to Google Earth, found my starting and ending locations and started zooming in and looking at buildings. The rest is history. This is why it takes time to post my photographs.

From Wikipedia, the free encyclopedia

Piazza Venezia is a major circus and the central hub of Rome, Italy, in which many thoroughfares intersect, like Via dei Fori Imperiali and Via del Corso. It takes its name from Venice ("Venezia" in Italian), after the Venetian Cardinal, Pietro Barbo (later Pope Paul II) who had built Palazzo Venezia, a palace set next to church of Saint Mark, also nearby, the patron saint of Venice. Palazzo Venezia was the former embassy of the city of the Republic of Venice to Rome.
The piazza or square is at the foot of the Capitoline Hill and next to Trajan's Forum. The main artery, the Viale di Fori Imperiali starts there, leading past the Roman Forum and to the Colosseum. It is dominated by the imposing Monument to Vittorio Emanuele II, first king of Italy.