A hop-on, hop-off bus loop past Molo Audace, the Roman Theatre, San Giusto Castle and Miramare, with an audio guide synced to the route in four languages. It’s the most-booked activity in Trieste by a wide margin, holding 4.4 across more than 2,500 verified reviews, and the ticket stays valid for 24 hours if you want to hop off along the way.