Goya, The Duchess of Alba. 1795.  María del Pilar Teresa Cayetana de Silva Alvarez de Toledo became the 13th Duchess of Alba (one of the oldest and most influential noble houses in Spain) in the year 1776. Her marriage to José María Alvarez de Toledo y Gonzaga, 15th Duke of Medina-Sidonia made the couplethe wealthiest couple in the Kingdom of Spain; their only rivals to this title were the House of Osuna.