Simply put, Port must come from the demarcated and regulated Douro Valley region in northern Portugal. By law, the grapes must be grown and the Port vinified within the appellation. It is the 3rd oldest demarcated wine region in the world, and the oldest to be both demarcated and regulated. The original boundaries were established in 1756 and they’ve been revised on several occasions since. The Douro River is in the northern part of Portugal and spans from the Atlantic Ocean at Porto eastward approximately 120 miles to Spain, where it continues as the Ribera del Duero for another 240 miles. The Port growing region, also known as the Alto Douro, begins near the village of Barqueiros about 40 miles upstream from Porto and continues all the way to the Spanish border.