La Rioja, in northern Spain, is known for its barrel-aged red wines, made primarily from Tempranillo grapes. It is arguably the best wine region in Spain. However, it is without a doubt the most famous. The vineyards follow the course of the river Ebro for about 100 kilometres between the towns of Haro and Alfaro. The Cantabrian mountain range flanks Rioja to the north and west, protecting the region from the cold and humid influences of the Atlantic Ocean. This is a crucial factor in the local climate, which is significantly warmer and drier than further north. The soils in this region vary from one place to another, with the finest soils containing high levels of limestone.