Cagliari (anc. Carales), the capital of the island of Sardinia, an archiepiscopal see, and the chief town of the province of Cagliari, which embraces the southern half of the island. It is 270 m. W.S.W. of Naples, and 375 m. south of Genoa by sea. Pop. (1900) of town, 48,098; of commune, 53,057. It is finely situated at the northern extremity of the Gulf of Cagliari, in the centre of the south coast of the island. The medieval town occupies a long narrow hill running N. and S. with precipitous cliffs on the E. and W. which must have been the ancient acropolis, but the modern town, like the Roman town before it, extends to the slopes of the hill and to the low ground by the sea. On each side of the town are lagoons. That of S. Gilla on the W., which produces fish in abundance, was originally an open bay. That of Molentargius on the E. has large saltpans. The upper town still retains in part its fortifications, including the two great towers at the two extremities, called the Torre dell' Elefante (S.) and the Torre di S. Pancrazio (N.), both erected by the Pisans, the former in 1307, the latter in 1305. The Torre di S. Pancrazio at the highest point (367 ft. above sea-level) commands a magnificent view. Close to it is the archaeological museum, the most important in the island.
To the north of it are the modern citadel and the barracks, and beyond, a public promenade. The narrow streets run from north to south for the whole length of the upper town. On the edge of the cliffs on the E. is the cathedral, built in 1257-1312 by the Pisans, and retaining two of the original transept doors. The pulpit of the same period is also fine: it now stands, divided into two, on each side of the entrance, while the lions which supported it are on the balustrade in front of the cathedral (see E. Brunelli in L'Arte, Rome, 1901, 59; D. Scano, ibid. 204). Near the sacristy are also some Gothic chapels of the Aragonese period. The church was, however, remodelled in 1676, and the interior is baroque. Two fine silver candelabra, the tabernacle and the altar front are of the 17th century; and the treasury also contains some good silver work. (See D. Scano in Bolletino d'Arte, February 1907, p. 14; and E. Brunelli in L'Arte, 1907, p. 47.) The crypt contains three ancient sarcophagi. The façade, in the baroque style, was added in 1703. The university, a little farther north, the buildings of which were erected in 1764, has some 240 students.
At the south extremity of the hill, on the site of the bastian of south Caterina, a large terrace, the Passeggiata Umberto Primo, has been constructed: it is much in use on summer evenings, and has a splendid view. Below it are covered promenades, and from it steps descend to the lower town, the oldest part of which (the so-called Marina), sloping gradually towards the sea, is probably the nucleus of the Roman municipium, while the quarter of Stampace lies to the west, and beyond it again the suburb of Sant' Avendrace. The northern portion of this, below the castle hill, is the older, while the part near the shore consists mainly of modern buildings of no great interest. To the east of the castle hill and the Marina is the quarter of Villanova, which contains the church of S. Saturnino, a domed church of the 8th century with a choir of the Pisan period. The harbour of Cagliari (along the north side of which runs a promenade called the Via Romo) is a good one, and has a considerable trade, exporting chiefly lead, zinc and other minerals and salt, the total annual value of exports amounting to nearly 1&FRAC12; million sterling in value.
The Campidano of Cagliari, the plain which begins at the north end of the lagoon of S. Gilla, is very fertile and much cultivated, as is also the district to the east round Quarto S. Elena, a village with 8459 inhabitants (1901). The national costumes are rarely now seen in the neighbourhood of Cagliari, except at certain festivals, especially that of S. Efisio (May 1-4) at Pula (see Nora). The methods of cultivation are primitive: the curious water-wheels, made of brushwood with pots tied on to them, and turned by a blindfolded donkey, may be noted. The ox-carts are often made with solid wheels, for greater strength. Prickly pear (opuntia) hedges are as frequent as in Sicily. Cagliari is considerably exposed to winds in winter, while in summer it is almost African in climate. The aqueduct was constructed in quite recent times, rain-water having previously given the only supply. The main line of railway runs north to Decimomannu (for Iglesias), Oristano, Macomer and Chilivani (for Golfo degli Aranci and Sassari); while another line (narrow-gauge) runs to Mandas (for Sorgono and Tortoli). There is also a tramway to Quarto S. Elena.
In A.D. 485 the whole of Sardinia was taken by the Vandals from Africa; but in 533 it was retaken by Justinian. In 687 Cagliari rose against the East Roman emperors, under Gialetus, one of the citizens, who made himself king of the whole island, his three brothers becoming governors of Torres (in the N.W.), Arborea (in the S.W.) and Gallura (in the N.E. of the island). The Saracens devastated it in the 8th century, but were driven out, and the island returned to the rule of kings, until they fell in the 10th century, their place being taken by four "judges" of the four provinces, Cagliari, Torres, Arborea and Gallura. In the 12th century Musatto, a Saracen, established himself in Cagliari, but was driven out with the help of the Pisans and Genoese. The Pisans soon acquired the sovereignty over the whole island with the exception of Arborea, which continued to be independent. In 1297 Boniface VIII. invested the kings of Aragon with Sardinia, and in 1326 they finally drove the Pisans out of Cagliari, and made it the seat of their government.
In 1348 the island was devastated by the plague described by Boccaccio. It was not until 1403 that the kings of Aragon were able to conquer the district of Arborea, which, under the celebrated Eleonora (whose code of laws - the so-called Carta de Logu - was famous), offered a heroic resistance. In 1479 the native princes were deprived of all independence. The island remained in the hands of Spain until the peace of Utrecht (1714), by which it was assigned to Austria. In 1720 it was ceded by the latter, in exchange for Sicily, to the duke of Savoy, who assumed the title of king of Sardinia (Cagliari continuing to be the seat of government), and this remained the title of the house of Savoy until 1861. Cagliari was bombarded by the French fleet in 1793, but Napoleon's attempt to take the island failed.