Capo D'Istria, a town of Istria, Austria, in a district of the same name, 8 m. S. S. E. of Trieste; pop. in 1869, 9,169. It occupies a nearly circular island, which is connected with the mainland by a stone causeway, built by the French in place of a former wooden bridge. The buildings are chiefly of a Venetian character, the most notable being the palazzo pubblico, built in an irregular Gothic style upon the site of an ancient temple of Cybele. The city has a good harbor, a cathedral, about 30 churches, two convents, an academy and gymnasium, an aqueduct, and extensive salt works. It is said to have been founded by the Colehians, under the name of AEgida. In the 6th century many wealthy families sought a refuge there from the Lombards and Avars. Having been conquered by the emperor Justinian I., it was named by him Justinopolis, in honor of his uncle Justin I. Later it became an independent commonwealth; was annexed to Venice in 932; conquered by the Genoese in 1380; fell again under Venetian supremacy about 100 years later; and was annexed to Austria in 1797.