Short answers, pulled from the story.
Archaeological evidence dates the earliest strata on the ground to the 9th century BC, though tradition places the founding around 1100 BC. The Phoenicians established a trading post on the narrow isthmus of southern Spain in the 7th century BC and named this settlement Gadir.
The city fell to Romans under Scipio Africanus in 206 BC after serving as a depot for Hannibal's conquest of southern Iberia. Roman citizenship was bestowed upon all inhabitants of the city in 49 BC, and an aqueduct provided fresh water to the town running across open sea for its final leg because the island supply was poor.
Under Moorish rule between 711 and 1262, the city was called Qādis, whence the modern Spanish name derives. The Moors were ousted by Alphonso X of Castile in 1262, and Frisian crusaders en route to the Holy Land burned the city and destroyed its congregational mosque in 1217.
The sand bars of the Guadalquivir forced the Spanish government to transfer American trade from Seville to Cádiz in 1717 so that Cádiz could command better access to the Atlantic Ocean. This new importance brought another golden age to the city despite the declining empire.
It was here that the liberal Spanish Constitution of 1812 was proclaimed on the 19th of March 1812 in Plaza San Antonio. Citizens revolted in 1820 to secure a renewal of this constitution, and the revolution spread successfully until Ferdinand VII was imprisoned in Cádiz.
The Cathedral of Cádiz known locally as the New Cathedral took 116 years to build from 1722 due to changes in design over that period. The largely Baroque-style cathedral underwent major changes and was completed in neoclassical style after Vicente Acero resigned before completion.