Cadiz (Spanish: Cádiz, pronounced: [ˈkaðiθ], locally: [ˈkaðis] ( listen) or [ˈka.i]; Phoenician: גדר, Gader; Arabic: قَادِس ) is a city and port in southwestern Spain. It is the capital of the homonymous province, one of eight which make up the autonomous community of Andalusia.

Cadiz, the oldest continuously-inhabited city in the Iberian Peninsula and possibly all southwestern Europe, has been a principal home port of the Spanish Navy since the accession of the Spanish Bourbons in the 18th century. The city is a member of the Most Ancient European Towns Network. It is also the site of the University of Cadiz.

Despite its unique site — on a narrow slice of land surrounded by the sea — Cadiz is, in most respects, a typically Andalusian city with a wealth of attractive vistas and well-preserved historical landmarks. The older part of Cadiz, within the remnants of the city walls, is commonly referred to as the Old Town (in Spanish, Casco Antiguo). It is characterized by the antiquity of its various quarters (barrios), among them El Pópulo, La Viña, and Santa María, which present a marked contrast to the newer areas of town. While the Old City's street plan consists of narrow winding alleys connecting large plazas, newer areas of Cadiz typically have wide avenues and more modern buildings. In addition, the city is dotted by numerous parks where exotic plants flourish, including giant trees supposedly brought to Spain by Columbus from the New World.