About 5. My mother's sister lived in Barcelona and her husband had a house on the Costa Brava, so several holidays there age 5-10. I was once sent on a plane as an unaccompanied minor to Barcelona, and there was no one there to meet me, and I was too young to know my aunt's address. Spent the night in a hotel with an air stewardess.
But, I loved my Spanish uncle. Far more than my parents.