The slanted building in the foreground is the Coliseum. What you see in the background is also Coliseum. The two parts are on two different ends of a C.
I actually spent quite some time around that site looking for a new angle of the stadium- I was trying to avoid just another typical shot of what may be one of the most photographed sites in the world. It took a bit of climbing up here and there before I finally saw this, when I changed into a telephoto and *clicked*. Handheld, at smallest aperture.