Santorini has such a deep and rich history that definitely should be explored on your next trip to the island. The Ancient Byzantine Castle is one of the best places to start your exploration of the history of the island. The Byzantine Empire played one of the most influential roles in the culture in history of ancient Greece. The empire was led by Christian rulers, who spread the Greek orthodox religion throughout the country. You can also visit the Akrotiri Archaeological Site which shows ruins from the bronze age, dating back to 1600 BC. Safe travels!