Iconic monuments — always free
Pantheon (€5 since 2023, free Sundays before 13:00 if pre-booked), Trevi Fountain, Spanish Steps, Piazza Navona with Bernini's Four Rivers fountain, Piazza del Popolo, Castel Sant'Angelo bridge, Roman Forum exterior views from Capitoline Hill, Mouth of Truth (Bocca della Verità) — €2 donation suggested.
Churches with priceless art (free)
St. Peter's Basilica (Bernini, Michelangelo's Pietà), San Luigi dei Francesi (3 Caravaggio paintings), Santa Maria del Popolo (2 Caravaggio), Sant'Ignazio (illusion ceiling), Santa Maria sopra Minerva (Michelangelo statue), San Pietro in Vincoli (Michelangelo's Moses, €1), Basilica di Santa Maria Maggiore.
Free state museums — first Sunday
Every first Sunday of the month, all state museums free: Colosseum, Roman Forum, Palatine, Castel Sant'Angelo, Galleria Borghese (still must book), Galleria Nazionale, Terme di Diocleziano. Expect huge crowds — arrive early.
Best free viewpoints
Janiculum Hill (Gianicolo), Pincio Terrace (Villa Borghese), Aventine Keyhole (Knights of Malta), Orange Garden (Giardino degli Aranci), Castel Sant'Angelo bridge at sunset, Piazza del Campidoglio at night.
Free parks & gardens
Villa Borghese (huge green park), Villa Doria Pamphilj (Rome's largest park), Villa Ada, Orange Garden on Aventine, Rose Garden (Roseto Comunale, May–June), Botanical Garden of Trastevere (€4 entry but worth it).
Free experiences
Watch the changing of the guard at Quirinale Palace (Sundays 16:00 in winter, 18:00 summer), attend Papal Angelus at noon Sunday, walk the entire Aurelian Walls (free, 19km circuit), explore Trastevere on foot at sunset, visit the Protestant Cemetery (Keats' grave, donation).