The Duomo di Udine, dedicated to Santa Maria Annunziata, is a 14th-century Romanesque–Gothic foundation extensively reworked in the 18th century. Inside, the most interesting works are the altar pieces and frescoes by Giambattista Tiepolo — his early Udine paintings made his name.
Look up in the side chapels and ceiling cycles to find his bright, airy compositions. Adjacent is the Oratorio della Purità, whose Tiepolo Assumption ceiling is sometimes opened on request through the cathedral sacristy.