getting there: from Via del Corso onto Via di San Claudio and across the piazza
open: 7:00-12:00 and afternoon
I found walking around Rome was the best way to see everything. The metro, trams and buses are an easy and cheap option also.
Most buses and metros do get crowded and tickets must be bought before boarding and validated when you first get on.
Beware of pickpockets.
Buses #40 (express) and #64 starts at Termini and ends near Saint Peter's, traveling past places of interest, returning the same way.
Some stops along the #64 route are:
Corso Vittorio Emanuele II
Bus #75 takes you past the Colosseum to Trastevere
Bus #910 takes you to Villa Borghese
€1.50 B.I.T (Biglietto Integrato a Tempo) is the standard ticket valid for one metro, unlimited tram or bus ride within a 100 minutes.
€7.00 B.I.G ( Biglietto Integrato a Giornaliero) is a daily ticket valid for unlimited metro, tram, bus and train travel within Rome.
Purchasing Bus and Metro tickets.
Newsstands, train stations, metro stations, kiosks with the ATAC logo and tabacchi shops sell tickets for the metro, trams and buses.
Large fines apply to travelers not holding or validating their ticket. Tickets once validated start from the time they have been stamped.