Isabella is born at the royal palace in Madrigal de las Altas Torres, Ávila, Castile.
Isabella I of Castile was born on 22 April 1451 at the royal palace in Madrigal de las Altas Torres, in the province of Ávila. She was the daughter of King John II of Castile and his second wife, Isabella of Portugal.
Her early years were shaped by the volatile politics of the Castilian court. Following her father's death in 1454, her half-brother Henry IV ascended the throne, and Isabella spent much of her childhood in relative seclusion in Arévalo with her mother and younger brother Alfonso, in modest and often precarious circumstances despite her royal status.
This modest upbringing, marked by uncertainty over succession and the machinations of rival noble factions, instilled in Isabella a deep religious devotion, a disciplined temperament, and a keen political awareness that would define her later reign. Few could have predicted at her birth that this princess, third in line to a contested throne, would grow to become one of the most consequential monarchs in European history, uniting the crowns of Castile and Aragon and presiding over the momentous events of 1492.