Postmarked Vila Nova de Gaia, dated 6 April 2009.
Wine has been produced by traditional landholders in the Alto Douro region for some 2,000 years. Since the 18th century, its main product, port wine, has been world famous for its quality. This long tradition of viticulture has produced a cultural landscape of outstanding beauty that reflects its technological, social and economic evolution.The Douro river is one of the major rivers in Portugal. It is one area of the Douro Valley which has been designated a UNESCO World Heritage Site. The area around Pinhão and São João da Pesqueira is considered to be the centre of port wine making. The wine is no longer transported in flat-bottomed boats, but in tanker trucks.