The Minho River runs between Spain and Portugal down to the Atlantic. While you can now easily drive either side of it, historically it was a hard border with ferry crossings and fortifications. Those have been replaced by a number of bridges and it now makes for a scenic drive or rail journey through what is world class white wine country growing Albariño and other grapes. The 70-kilometer stretch between Tui in the west to Ribadavia in the east is mostly along the border (which cuts into Spain partway) and is enough for a diversion or a day trip. Tui is accessible off the main north-south A3 (Portugal)/ A55 (Spain) highway and Ribadavia via the city of Ourense.
The Minho region is unspoiled and off the larger tourism routes that lead to Santiago de Compostela and Porto – both of which are only a few hour’s drive away. Large winery tracts descend into the river valley. A map search provides multiple winery locations and each country’s respective Minho tourism board provide pointers as to where to go.
The riverfront town of Ribadavia is easily overlooked and is a very well-preserved medieval fort town that deserves a stop. As the unofficial capital of the Ribeiro wine region, regional wines get good coverage and there are frequent wine festivals (including an annual fair each April) to check ahead for. Ribadavia once had a significant Jewish quarter with a community that survived the expulsions of 1492, echoed in Sephardic recipes still made in the local bakery, Tahona da Herminia.
Rúa da Xudería is at the center of the quarter and there is a Jewish information center is above the tourist office. You can take the regional train along the Minho to Ribadavia if the car doesn’t appeal but check your starting city – Ourense and Vigo are n the line but you can connect from other cities: http://www.renfe.com/EN/viajeros/mediadistancia/mapas_y_trayectos/Galicia.html
There are plenty of wineries either side of the river, focusing on white and rose, including the various Portuguese Vinho Verde dry whites. Albarino/Alvarino is also popular and tends to be fuller-bodied. For example, the Quinta Edmun do Val winery located in São Julião, about 12 km south of Valença in Portugal, produces an aged Alvarino which has some great dry sherry notes and is worth a visit.
Most of the cities along the river are pleasant enough for stopovers – including Valenca and Moncao in Portugal. If you want to include a beach stop, Guarda in Spain and Viano do Castelo in Portugal are where to head for.