The Rabelo boat was invented in the 9th century. Transporting products from the farms of the Douro River for centuries. The purpose of its peculiar shape was to overcome the natural obstacles of the Douro river and to make the boatman's task easier. The large amount of Port Wine produced in the farms required frequent transportation downriver. The journey lasted more than a week and the conditions were precarious. One of Oporto's Main Symbols.