The 50, 20 and 10 doubloon pieces, which were the largest multiples of gold coinage of the Catholic monarchs, were exponents of the political and economic strength of the Crown of Castile started to acquire in Europe,. They were not designed to circulate as coins, but were to be used as figurative pieces, given as gifts at formal occasions. Minted in Seville and Segovia, these unique coins belong to the Castilian system introduced in 1497. The marriage of Isabel and Ferdinand, which led to the dynastic union of Castile and Aragon, resulted in the start of a long and complex process that many years later would result in the transformation of the medieval kingdoms into one State. The different monetary reforms played an important role in the modernisation programme. The new coins fulfilled an economic need, but their typology was a true propaganda vehicle. Thus, on the doubloons Isabel and Ferdinand are shown together, a symbol of unity and harmony between the two Crowns, along with the arms of all of their kingdoms.