Final answer:
Spain's first settlement in Florida was located at St. Augustine, established in 1565 and is the oldest continuously-settled European settlement in the United States.
Step-by-step explanation:
Spain's first settlement in Florida was located at St. Augustine. This historic site was established by Pedro Menéndez de Avilés in 1565, south of Fort Caroline. St. Augustine's success is notable as it is the oldest continuously-settled European settlement in the continental United States. The settlement served as a strategic post against French Huguenots at Fort Caroline and became a bastion against the English and French privateers who posed a significant threat to Spanish treasure fleets along their shipping lanes. The strong relationship with the local Timucua Indians and the strategic positioning of St. Augustine played a critical role in its longevity and in the Spanish maintaining a foothold in North America.