valleys in this area. Between them lies the flat and forested Holzland in the north, the flat and fertile Orlasenke in the middle and the Vogtland, a hilly but in most parts non-forested region in the south. The far eastern region (east of White Elster) is the Osterland or Altenburger Land along Pleiße river, a flat, fertile and densely settled agricultural area. There are two large rivers in Thuringia. The Saale, a tributary of the Elbe, with its tributaries the Unstrut, Ilm and White Elster, drains the most part of Thuringia. The Werra – the headwater of the Weser – drains the south-west and west of the state. Furthermore, some small areas on the southern border are drained by tributaries of the Main, itself a tributary of the Rhine. There are no large natural lakes in Thuringia, but it does have some of Germany's biggest dams, including the Bleiloch Dam and the Hohenwarte Dam on the River Saale, as well as the Leibis-Lichte Dam and the Goldisthal Pumped Storage Station in the Thuringian Highlands. Thuringia is Germany's only state with no connection to navigable waterways. The geographic centre of the Federal Republic is in Thuringia, within the municipality of Vogtei next to Mühlhausen. The centre of Thuringia is eight kilometres south of the capital's Cathedral, in the municipality of Rockhausen. Climate Thuringia's climate is temperate with humid westerly winds predominating. Increasingly as one moves from the north-west to the south-east, the climate shows continental features: winters can be cold for long periods, and summers can become warm. Dry periods are often recorded, especially within the Thuringian Basin, leeward to mountains in all directions. It is Germany's driest area, with annual precipitation of only 400 to 500 mm. Artern, in the north-east, is warm and dry, with a mean annual temperature of 8.5 °C and mean precipitation of 450 mm; contrast this with wet, cool Oberhof, in the Thuringian Forest, where temperature averages only 4.4 °C and mean annual precipitation reaches 1300 mm. Nature and environment Due to many centuries of intensive settlement, most of the area is shaped by human influence. The original natural vegetation of Thuringia is forest with beech as its predominant species, as can still be found in the Hainich mountains today. In the uplands, a mixture of beech and spruce would be natural. However, most of the plains have been cleared and are in intensive agricultural