The region of Rioja is one of the most prestigious wine growing areas in all of Spain. Located in the northern part of the country, Rioja possesses a continental climate that is shielded from the ocean by the Cantabrian Mountain Range. Summers here can be quite hot and allow for ripening of varietals such as Tempranillo, Garnacha, and Graciano. Although wine production in the area has been going on for thousands of years it was not until the mid-1800's that Rioja truly emerged as a region of superior quality. By modeling their production after the wines of Bordeaux and incorporating the use of new oak barrels, producers in Rioja began crafting wines that garnered significant recognition. Due to the high cost of procuring French oak many producers switched over American oak which was significantly more affordable, although this consequently and famously added slight notes of dill to the finished wines. Rioja wine is classified into four levels of quality: Rioja, Rioja Crianza, Rioja Riserva, and Rioja Gran Reserva. The higher quality bottlings see longer aging in oak and bottle before release, and typically also are made using a producer's finest fruit. Despite the storied and famed nature of its wines Rioja still remains relatively affordable and high-end bottles are known to be some of the longest lived wines in the world.