Medina-Sidonia is a city and municipality in the province of Cádiz in the autonomous community of Andalusia, southern Spain. It is considered by some to be the oldest city in Europe, used as a military defense location due to its elevated location. Locals are known as Asidonenses. The city's name comes from Medina (Arabic for city) and Sidonia (of Sidon), meaning "City of Sidon".

Medina-Sidonia was one of Spain's most important ducal seats in the 15th century; producing an admiral, Alonso Pérez de Guzmán, 7th Duke of Medina Sidonia, who led the Spanish Armada against England in 1588. The title of Duque de Medina Sidonia was bestowed upon the family of Guzmán El Bueno for his valiant role in taking the town. The line continues and was led until March 2008 by the controversial socialist, Luisa Isabel Álvarez de Toledo, 21st Duchess of Medina Sidonia (born 1936).