The article brings twelve unknown designs and projects of Rijeka’s sculptor and altar maker Antonio Michelazzi (Gra- disca d’Isonzo, 1707 – Rijeka, 1771). The earliest two designs, dating from 1750 and linked to the island of Krk, are today preserved at the Archivio di Stato in Venice. One is a ground plan and assessment of a public ruin in the town of Krk, and the other a panoramic view of the Omišalj bay. A newly discovered document clarifies Michelazzi’s commissioning by the Trieste administration in charge of Rijeka, Senj, and Karlobag, since Empress Maria Theresa appointed him the imperial-royal architect in 1755. In that capacity, Michelazzi worked on a dozen plans and projects for public works in Senj and Karlobag during 1757 and 1758. He drew a map of Senj with a project for modernizing the city port and its defence against stormy winds. A particularly important project was his plan to redirect the stream that ran through the town into the harbour of Senj, for which he designed a new riverbed. There were also projects for prisons in the citadel, a health office, a slaughterhouse, and butcher shops. In Karlobag, he made a project for the renovation of the citadel, butcher shops, a new cistern, and a public administrative-residential building on the main town square. His last design and project was a new slaughterhouse with butcher shops in Rijeka in 1770. Although most of Michelazzi’s designs were never put in practice because of the lack of finances, the designs published here are the first of this kind in his known oeuvre, which will certainly grow further, since he was also involved in architecture besides sculpture and altar making.