Tvrdalj was built as a fort for defence from the Turks by the renowned poet from Hvar Petar Hektorović. It was erected by filling up the sea and one could enter it only over a bascule bridge. In the centre of Tvrdalj, Hektorović designed and built a Romanic park with a fishpond. Tvrdalj has numerous stone inscriptions, but the one saying 'Omnium Conditori' is the most significant one, since, with it, Hektorović dedicated his Tvrdalj to God, the Creator of everything.
https://www.visit-hvar.com/tours/tvrdalj-stari-grad/HV-TR-24