The San Giusto Cathedral (full name: Cattedrale di San Giusto Martire) is worth visiting even for those who aren’t particularly fond of churches, thanks to its impressive mosaics. You can find the cathedral in the city center, at the top of San Giusto hill, next to the castle. The cathedral was created by uniting two churches: the Church of Saint Mary and the church of the city’s patron saint, Saint Justus the Martyr. The unification was carried out by the bishop at the time, Roberto Pedrazzani da Robecco, between 1302 and 1320. In the church, you can see Roman-era carved stones used in its construction and the fifth-century mosaic floor from the earlier church, while the frescoes were painted in the 13th century. The main altar was consecrated on November 27, 1385, by Trieste’s first German bishop, Henry of Wildenstein, who was appointed by the Austrian Emperor Leopold III.
The bell tower next to the cathedral still offers excellent views, although it was originally taller but was shortened after being struck by lightning in 1422.
You can find the cathedral and bell tower opening hours here, and the Mass schedule here.