Aalen () is a former Free Imperial City located in the eastern part of the German state of Baden-Württemberg, about east of Stuttgart and north of Ulm. It is the seat of the Ostalbkreis district and is its largest town. It is also the largest town in the Ostwürttemberg region. Since 1956, Aalen has had the status of Große Kreisstadt (major district town). It is noted for its many half-timbered houses constructed from the 16th century through the 18th century. With an area of 146.63 km2, Aalen is ranked 7th in Baden-Württemberg and 2nd within the Government Region of Stuttgart, after Stuttgart. With a population of about 66,000, Aalen is the 15th most-populated settlement in Baden-Württemberg. Geography Situation Aalen is situated on the upper reaches of the river Kocher, at the foot of the Swabian Jura which lies to the south and south-east, and close to the hilly landscapes of the Ellwangen Hills to the north and the Welland to the north-west. The west of Aalen's territory is on the foreland of the eastern Swabian Jura, and the north and north-west is on the Swabian-Franconian Forest, both being part of the Swabian Keuper-Lias Plains. The south-west is part of the Albuch, the east is part of the Härtsfeld, these two both being parts of the Swabian Jura. The Kocher enters the town's territory from Oberkochen to the south, crosses the district of Unterkochen, then enters the town centre, where the Aal flows into it. The Aal is a small river located only within the town's territory. Next, the Kocher crosses the district of Wasseralfingen, then leaves the town for Hüttlingen. Rivers originating near Aalen are the Rems (near Essingen, west of Aalen) and the Jagst (near Unterschneidheim, east of Aalen), both being tributaries of the Neckar, just like the Kocher. The elevation in the centre of the market square is relative to Normalhöhennull. The territory's lowest point is at the Lein river near Rodamsdörfle, the highest point is the Grünberg's peak near Unterkochen at . Geology Aalen's territory ranges over all lithostratigraphic groups of the South German Jurassic: Aalen's south and the Flexner massif are on top of the White Jurassic, the town centre is on the Brown Jurassic, and a part of Wasseralfingen is on the Black Jurassic. As a result, the town advertises itself as a "Geologist's Mecca". Most parts of the territory are on the Opalinuston-Formation (Opalinum