2 Best Sights in Trieste, The Veneto and Friuli–Venezia Giulia

Dating from the 14th century and occupying the site of an ancient Roman forum, the cathedral contains remnants of at least three previous buildings, the earliest a hall dating from the 5th century. A section of the original floor mosaic still remains, incorporated into the floor of the present church. In the 9th and 11th centuries two adjacent churches were built—the Church of the Assumption and the Church of San Giusto. The beautiful apse mosaics of these churches, done in the 12th and 13th centuries by a Venetian artist, still remain in the apses of the side aisles of the present church. The mosaics in the main apse date from 1932. In the 14th century the two churches were joined and a Romanesque-Gothic facade was attached, ornamented with fragments of Roman monuments taken from the forum. The jambs of the main doorway derive from Roman funereal stelae.

This small Romanesque gem, dating from the 9th to the 12th centuries, is the oldest church in Trieste that's still in use and in approximately its original form. Its interior walls have some fragmentary remains of Romanesque frescoes. The church was deconsecrated under the secularizing reforms of the Austrian emperor Josef II in 1785 and was later sold to the Swiss Evangelical community; it then became, and is still, the Reformed Evangelical and Waldensian Church of Trieste.