Cadiz (in Lat. Gades, and formerly called Cales by the English), the capital and principal seaport of the Spanish province of Cadiz; on the Bay of Cadiz, an inlet of the Atlantic Ocean, in 36° 27′ N. and 6° 12′ W., 94 m. by rail S. of Seville. Pop. (1900) 69,382. Cadiz is built on the extremity of a tongue of land, projecting about 5 m. into the sea, in a north-westerly direction from the Isla de Leon. Its noble bay, more than 30 m. in circuit, and almost entirely land-locked by the isthmus and the headlands which lie to the north-east, has principally contributed to its commercial importance. The outer bay stretches from the promontory and town of Rota to the mouth of the river Guadalete; 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, a broad channel separating the Isla de Leon from the mainland.

At the mouth of this channel is the village of Caracca; close beside it is the important naval arsenal of San Fernando (q.v.); and on the isthmus are the defensive works known as the Cortadura, or Fort San Fernando, and the well-frequented sea-bathing establishments.

From its almost insular position Cadiz enjoys a mild and serene climate. The Medina, or land-wind, so-called because it blows from the direction of Medina Sidonia, prevails during the winter; the moisture-laden Virazón, a westerly sea-breeze, sets in with the spring. The mean annual temperature is about 64° F., while the mean summer and winter temperatures vary only about 10° above and below this point; but the damp atmosphere is very oppressive in summer, and its unhealthiness is enhanced by the inadequate drainage and the masses of rotting seaweed piled along the shore. The high death-rate, nearly 45 per thousand, is also due to the bad water-supply, the water being either collected in cisterns from the tops of the houses, or brought at great expense from Santa Maria on the opposite coast by an aqueduct nearly 30 m. long. An English company started a waterworks in Cadiz about 1875, but came to grief through the incapacity of the population to appreciate its necessity.

The city, which is 6 or 7 m. in circumference, is surrounded by a wall with five gates, one of which communicates with the isthmus. Seen from a distance off the coast, it presents a magnificent display of snow-white turrets rising majestically from the sea; and for the uniformity and elegance of its buildings, it must certainly be ranked as one of the finest cities of Spain, although, being hemmed in on all sides, its streets and squares are necessarily contracted. Every house annually receives a coating of whitewash, which, when it is new, produces a disagreeable glare. The city is distinguished by its somewhat deceptive air of cleanliness, its quiet streets, where no wheeled traffic passes, and its lavish use of white Italian marble. But the most characteristic feature of Cadiz is the marine promenades, fringing the city all round between the ramparts and the sea, especially that called the Alameda, on the eastern side, commanding a view of the shipping in the bay and the ports on the opposite shore.

The houses are generally lofty and surmounted by turrets and flat roofs in the Moorish style.

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. Of its two cathedrals, one was originally erected by Alphonso X. of Castile (1252-1284), and rebuilt after 1596; the other, begun in 1722, was completed between 1832 and 1838. Under the high altar of the old cathedral rises the only freshwater spring in Cadiz. The chief secular buildings include the Hospicio, or Casa de Misericordia, adorned with a marble portico, and having an interior court with Doric colonnades; the bull-ring, with room for 12,000 spectators; the two theatres, the prison, the custom-house, and the lighthouse of San Sebastian on the western side rising 172 ft. from the rock on which it stands. Besides the Hospicio already mentioned, which sometimes contains 1000 inmates, there are numerous other charitable institutions, such as the women's hospital, the foundling institution, the admirable Hospicio de San Juan de Dios for men, and the lunatic asylum. Gratuitous instruction is given to a large number of children, and there are several mathematical and commercial academies, maintained by different commercial corporations, a nautical school, a school of design, a theological seminary and a flourishing medical school.

The museum is filled for the most part with Roman and Carthaginian coins and other antiquities; the academy contains a valuable collection of pictures. In the church of Santa Catalina, which formerly belonged to the Capuchin convent, now secularized, there is an unfinished picture of the marriage of St Catherine, by Murillo, who met his death by falling from the scaffold on which he was painting it (3rd of April 1682).

Cadiz no longer ranks among the first marine cities of the world. Its harbour works are insufficient and antiquated, though a scheme for their improvement was adopted in 1903; its communications with the mainland consist of a road and a single line of railway; its inhabitants, apart from foreign residents and a few of the more enterprising merchants, rest contented with such prosperity as a fine natural harbour and an unsurpassed geographical situation cannot fail to confer. Several great shipping lines call here; shipbuilding yards and various factories exist on the mainland; and there is a considerable trade in the exportation of wine, principally sherry from Jerez, salt, olives, figs, canary-seed and ready-made corks; and in the importation of fuel, iron and machinery, building materials, American oak staves for casks, etc. In 1904, 2753 ships of 1,745,588 tons entered the port. But local trade, though still considerable, remains stationary if it does not actually recede. Its decline, originally due to the Napoleonic wars and the acquisition of independence by many Spanish colonies early in the 19th century, was already recognised, and an attempt made to check it in 1828, when the Spanish government declared Cadiz a free warehousing port; but this valuable privilege was withdrawn in 1832. Among the more modern causes of depression have been the rivalry of Gibraltar and Seville; the decreasing demand for sherry; and the disasters of the Spanish-American war of 1898, which almost ruined local commerce with Cuba and Porto Rico.