There is a Greek village (represented by the Byzantines, green) nearby, who during the game will offer to join you for 800 Gold . Once they've joined you, they'll start tributing you resources, quickly repaying their cost, and more.
One way to keep the enemy forces from destroying your wonder, is to not start building it immediately, but instead focus on creating soldiers to meet their forces. The foundation is placed at the start of the game, but if you haven't started building it, there is nothing there to destroy. Once most of the enemy forces has been dealt with, you can start building.