Antoninus Pius was emperor of the Roman Empire when the Romans had occupied the island of Crete. That is why you can see his statue on the archeological site of Gortyna.
He never visited Crete but he was a very beloved emperor known for his peacefull way of ruling the whole Roman empire of that time without ever leaving Italy. He ruled over the whole meditarenean area as also Great Britain.
This olive tree probably saw the Romans build the tempel and odeon in the ancient city of Gortyna during the first century AD. But it also saw the city being destroyed by the Arabs in 828AD. After this destruction live was quiet around it, and then from the 19th century on escavations started in the area and the tree came to its right as all these years it was embrasing and protecting a pillar put there by the Romans.