ortugal has the oldest appellation system in the world, the Douro Valley. This region and the Vinho Verde region in the northwest produce some of the finest, most unique and value-added wines in the world. The Alentejo and Dão regions produce wines with fertile flavors, suitable for the occasional wine drinker. Portugal has two wine regions protected by UNESCO as World Heritage Sites: the Douro Valley Wine Region (Douro Vinhateiro) and the Pico Island Wine Region (Ilha do Pico Vinhateira). Portugal has a wide variety of indigenous breeds (about 500), producing a very wide variety of different wines with a personality of distinctive. The Oxford Companion to Wine describes the country as having "a treasure trove of indigenous grape varieties. With the quality and uniqueness of its wines, the country is an important and growing player in wine production, being in the top 10, with 4% of the world market (2003). The country is considered a traditional winemaker with 8% of its continental land dedicated to vineyards. Only the highest mountain peaks are unable to support viticulture. Portugal produces some of the best wines in the world, as evidenced by its success in international competitions. The type of grapes (castas) is as important as the type of soil and climate, creating the different breeds of Portuguese wine, the Castas - grape varieties. It produces distinctive wines from the northern regions to the Madeira Islands, through the Algarve and the Azores. The particular race of wines makes Portugal a country with a distinctive personality in terms of Viti vineyard. But this distinctive character brings more difficulties than advantages, due to the fact that it would be easier to produce international wine varieties.