Answer based on context:

During the 14th century, the Mendoza family was prominent in Guadalajara. This family included Íñigo López de Mendoza, also known as Marqués de Santillana , and Pedro González de Mendoza , Great Cardinal of Spain and adviser of the Catholic Monarchs. The Mendoza family held the title of Dukes and Duchesses of El Infantado from 1475. In 1460, King Henry IV gave Guadalajara the title of 'City' and other privileges like the Cortes. Guadalajara was the birthplace of conquistador Nuño de Guzmán, who commissioned in 1542 the foundation of Guadalajara, Mexico. During the War of the Spanish Succession, Guadalajara was sacked. King Philip V ordered the establishment of the Real Fábrica de Paños  which was situated in the Alcazar till the early 19th century. In this period, the Mendoza Family ordered the building of El Palacio del Infantado as their main residence. It was completed in the early 1480s and it is considered by many the oldest surviving building built in a pure Renaissance style outside Italy.

How many years after Guadalajara was given the title of 'City' was the El Palacio del Infantado completed?
20