of May 2005). But because of Aquileias size, location and other indicators, it is believed that it probably was the capital of a Roman administrative district (see also Civitas). From 233 on, the Alamanni repeatedly attacked the Roman limes fortifications. The Roman surrender of the limes in 260 spelled the end of the Roman city of Heidenheim. It is not clear to what extent Romans stayed on under the new, Alammanic rule but it is very likely that some did. Nothing is known about Aquileia/Heidenheim during the period of the Great Migration. However, already in the 8th century Heidenheim was mentioned (again) for the first time in official documents. The creation of the city in the Middle Ages went hand in hand with the construction of Hellenstein Castle. The city wall was built in segments in 1190 and 1420 and Emperor Charles IV granted or confirmed the city as a market town in 1356. Through the rule of the von Helfenstein family, the city became part of the Duchy of Teck of ruled by Württemberg in 1448. It temporarily belonged to the dukes of Bavaria between 1462 and 1504. Later yet, and for a short time only, the city belonged to Ulm. During Württemberg times, it was always the seat of an administrative unit. This unit was an exclave of the dukes of Württemberg until 1803 when Württemberg's territorial gains connected the city with the main part of the duchy's territory. In 1807 Heidenheim was promoted to district status and then again to County status in 1938. The district reform in the 1970s did not change the county limits by much. The economic development of the village and city is founded mainly on the area's ore deposits that were already being harvested in Roman times. However, the importance of this branch of the city's economy vanished near the turn of the 19th century due to great competition first from Wasseralfingen and later from the Rhineland. Heidenheim played an important part also in the textile industry. Flax grown in the Eastern Swabian Alb was used to manufacture linen. The business grew into an industry at the dawn of the 19th century with the help of cotton imports but declined after World War II due to international competition. During the war, a subcamp of the Dachau concentration camp was located here. It provided slave labour to local industry. After World War II