In the Middle Ages the name of the city was Culus, as attested in documents of 1173, but by the beginning of the 15th century it was known as Cluj (probably from Castrum Clus, a small fortification dating from 1213). The city has also been known by its German name, Klausenburg, and its Hungarian name, Kolozsvár. It became a thriving commercial and cultural centre, and in 1405 it was declared a free town. After the constitution of the autonomous principality of Transylvania in the 16th century, Cluj became its capital. In 1920 the city, with the rest of Transylvania, was incorporated into Romania. Napoca was added to the city's name in 1974.

Among the historic monuments are the house in which Matthias I Corvinus (king of Hungary, 1458–90) was born; the Roman Catholic cathedral of St. Michael (1321–1444), one of the largest Gothic churches in Romania; and the Bánffy Palace (1773–85), now a fine arts museum. The city is the location of the Babeș-Bolyai University, several technical and professional institutes, the Ion Andreescu Institute of Fine Arts, the Gheorghe Dima Conservatory, and a branch of the Academy of Romania. The institute of speleology was the first of its kind in the world. The botanical gardens are considered to be the richest in Romania.

Industrial progress has been substantial since the union with Romania. Cluj-Napoca's products include refrigerating equipment for industrial and domestic use, footwear and leather products, china, cigarettes, and foodstuffs. Pop. (2007 est.) 310,243.