What is where does the last name castro come from?

The last name Castro originated in Spain and is derived from the Latin word "castrum," which means "fortress" or "castle." It is believed that the name was first used to describe those who lived near a castle or fortress. The name was also adopted by several prominent families who owned and ruled over castles throughout Spain, Portugal, and other parts of Europe. Today, the surname is most commonly found in Spain, Portugal, Italy, and Latin America.