Museums/monuments with entrance fees, like the Vatican Museums, can be booked in advance or you can still wait in line for a ticket. All of Rome’s churches, as well as the Pantheon, are free to enter but there are no skip-the-line services for churches in Rome.

Here is a list of the Rome’s top free sites:

 

Pantheon

Trevi Fountain

Spanish Steps

Piazza Navona

Largo Argentina (Teatro Pompei can be seen from street level)

Campo dei Fiori

Tiber Island

Villa Borghese

Villa Pamphili