Here's what Trippy members say about Teatro di Marcello:
"The usual suspects aside (Coloseum, Spanish Steps, Capitoline and Forum, Piazza della Rotonda and Piazza Navona) you may want to also visit the Villa Borghese Gardens (and stunning scupture gallery), the Castel Sant'Angelo(amazing sunset views), the Teatro di Marcello, the Forum Boarium and the nearby Bocca della Verità at Basilica di Santa Maria in Cosmedin and the Giardino Degli Aranci on the Aventine Hill(where you can also find St Peter's keyhole)." See More