Which country colonized Panama?

The Spaniards colonized Panama in the early-to-mid 16th century and the most commonly proposed date is 1538. (The reason the date is vague is because Panama was part of the larger Spanish colony of Nueva Granada and was thus not considered individually important.) Panama was under Spanish control for roughly 300 years before choosing to join the new country of Gran Colombia with Colombia, Venezuela, and Ecuador in 1821. Although these other countries broke off from Gran Colombia relatively soon after, Panama remained attached to Colombia until the beginning of the 20th century. Panama finally gained full independence in 1903 with the assistance of the United States Navy.