I actually met with Rome's Department of Mobility when studying abroad there last year with a city planning program (cornell in rome) and not only are they building this new line (Line C), they're also extending both existing lines and even plan to build a fourth line (Line D). Historically Rome's metro has served to shuttle commuters as opposed to tourists, as the central city relies on ATAC's at times countless buses and the heavy rail lines handle the rest. But this new subway line travels under the historic center with it's medieval street pattern and ancient buildings. It's very exciting and going to be quite the awesome juxtaposition to have modern subway stations in this type of urban fabric. It also will relieve the at times ridiculous congestion in the center's main avenues, and probably aid the push for a complete pedestrianization of the historic center.
For a map go here:
http://www.romametropolitane.it/Roma...opolitane.html and click on "Mappa Metro" on the top.