The wine received its name , `` Port , '' in the second half of the 17th century from the seaport city of Porto at the mouth of the Douro River . Much of the product was brought there . The wine received its name , `` Port '' , in the latter half of the 17th century from the seaport city of Porto at the mouth of the Douro River , where much of the product was brought to market or for export to other countries in Europe .