Cadiz is the see of a bishop, who is suffragan to the archbishop of Seville, but its chief conventual and monastic institutions have been suppressed. Its noble bay, more than 30 miles in circuit and almost entirely land-locked by the isthmus and the headlands which lie to the N.E., has principally contributed to its commercial importance. The outer bay stretches from the promontory and town of Rota to the mouth of the Guadalete; and the inner bay, protected by the forts of Matagorda and Puntales, affords generally good anchorage, and contains a harbour formed by a projecting mole, where vessels of small burden may discharge. The entrance to the bays is rendered somewhat dangerous by the low shelving rocks (Cochinos and Las Puercas), which encumber the passage, and by the shifting banks of mud deposited by the Guadalete and the Rio Santi Petri. On the mainland, at the mouth of the latter river, is the village of Caracca, which contains about 6000 inhabitants, and possesses a naval arsenal and dockyard; and on the isthmus are situated the well-frequented sea-bathing establishments.

The commercial greatness of Cadiz is no longer what it was in the 17th and 18th centuries. At one time it was the great focus of intercourse between Spain and the Spanish colonies; and from 1720 to 1765 it enjoyed a monopoly of the traffic with Spanish America, which had previously been in the hands of Seville. Its prosperity began to decline when the trade of San Domingo, Cuba, Porto Rico, and the other islands was opened up to the greater ports of Spain, and decayed almost entirely in the beginning of the present century, when the colonies achieved their independence. An attempt was made by the Spanish Government in 1828 to restore its former greatness, by making it a free warehousing port, but this valuable privilege was withdrawn in 1832. Since the opening of the railway to Seville and the improvements effected in the harbour, the commercial activity has greatly increased; and in spite of the disturbing influences of political revolutions, Cadiz is still one of the most important ports in Spain. It is the European terminus of many of the principal mail-lines from the colonies both in the east and west. Besides the Xeres wine, for which it received in 1872 no less than £2,458,487 from Britain alone, it exports quicksilver, brandy, oil, provisions, flour, and wool. The salt trade, which was formerly of considerable extent, is almost extinct. The imports consist chiefly of sugar and coffee from Havana and Porto Rico, English coal from Cardiff, cocoa, hemp, flax, linens, dried fish, hides, cotton and woollen manufactures, rice, spices, indigo, staves, and timber. The total number of vessels that entered in 1872 was 1140, of which 494 were steamships; and the total tonnage was 287,850. Of the sailing vessels 179 were British and 136 Italian, of the steamships 127 British and 281 Spanish. The manufactures of Cadiz are unimportant, though a considerable stimulus to industry is given by the Sociedad economica de Amigos del Pais, which introduced the cochineal plant, and grants medals for improvements in manufactures.

Cadiz is strongly fortified with ramparts and bastions, and defended by the forts of San Sebastian, Santa Catalina, Matagorda, and Puntales Castle. On the neighbouring coast the isthmus is protected by an intrenchment called the Cortadura, or Fort San Fernando.

From its almost insular position it enjoys a mild and serene climate, the mean annual temperature being about 64° Fahr., while the mean summer and winter temperatures vary only about 10° above and below this point. From the same cause it labours under a great deficiency of water, which must either be collected in cisterns from the' tops of the houses or brought at great expense from Santa Maria on the opposite coast. Population in 1845, 53,922, and in 1860, 71,521.

Cadiz is identical with the ancient Agadir, Gadir, or Gaddir (in Greek Gαdeirα), which was a flourishing Phoenician colony long before the beginning of classical history, and continued in the hands of the Carthaginians, though somewhat disaffected to them, till after the Punic wars, when Spain became a Roman province. C. Julius Caesar conferred the civitas of Rome on all its citizens in 49 B.c.; and not long after L. Cornelius Balbus Minor built what was called the “New City,” constructed the harbour which is now known as Puerto Real, and erected the bridge across the strait of Santi Petri, which unites the Isla de Leon with the mainland, and is now known as the Puente de Zuazo, after Juan Sanchez de Zuazo, who restored it in the 15th century. Under Augustus, when it was the residence of no fewer than 500 equites, it was made a municipium with the name of Augusta Urbs Gaditana, and its citizens ranked next to those of Rome. Some remains of the ancient city, and particularly of the temple of Hercules, are said to be visible below the sea. After the fall of Rome it was destroyed by the Goths, and remained in obscurity under the Moors, from whom it was retaken by Alphonso the Wise in 1262, but it emerged again when the discovery of America made it valuable as a market for colonial produce. In more recent contests Cadiz has been subjected to several disasters. It was taken and pillaged in 1596 by the British fleet, under Essex and Howard, in revenge for the Spanish Armada. It was attacked, but without success, by Lord Wimbledon in 1626, and by the duke of Ormond and Sir George Rooke in 1702. It was bombarded by Nelson in 1800. In 1808 the Spanish patriots in Cadiz brought the French fleet, which lay in the bay blockaded by Admiral Collingwood, to a surrender; and they were in turn subjected to a protracted siege of two years by Marshal Victor, from which they were relieved by the successes of Wellington in the Peninsula. It was once more reduced by the Duke d’Angoulême in 1823, and remained in the hands of the French till 1828. In 1868 the city was the centre of the revolution which effected the dethronement of Queen Isabella.