Aare found part of a seven-meter wide wooden bridge from the late Roman times. Middle Ages Aarau was founded around AD 1472 by the counts of Kyburg. Aarau is first mentioned in 1248 as Arowe. Around 1250 it was mentioned as Arowa. However the first mention of a city sized settlement was in 1256. The town was ruled from the "Rore" tower, which has been incorporated into the modern city hall. In 1273 the counts of Kyburg died out. Agnes of Kyburg, who had no male relations, sold the family's lands to King Rudolf I von Habsburg. He granted Aarau its city rights in 1283. In the 14th century the city was expanded in two stages, and a second defensive wall was constructed. A deep ditch separated the city from its "suburb;" its location is today marked by a wide street named "Graben" (meaning Ditch). In 1415 Bern invaded lower Aargau with the help of Solothurn. Aarau capitulated after a short resistance, and was forced to swear allegiance to the new rulers. In the 16th century, the rights of the lower classes were abolished. In March 1528 the citizens of Aarau allowed the introduction of Protestantism at the urging of the Bernese. A growth in population during the 16th Century led to taller buildings and denser construction methods. Early forms of industry developed at this time; however, unlike in other cities, no guilds were formed in Aarau. On 11 August 1712, the Peace of Aarau was signed into effect. This granted each canton the right to choose their own religion thereby ending Catholicism's control. Starting in the early 18th century, the textile industry was established in Aarau. German immigration contributed to the city's favorable conditions, in that they introduced the cotton and silk factories. These highly educated immigrants were also responsible for educational reform and the enlightened, revolutionary spirit that developed in Aarau. 1798: Capital of the Helvetic Republic On 27 December 1797, the last Tagsatzung of the Old Swiss Confederacy was held in Aarau. Two weeks later a French envoy continued to foment the revolutionary opinions of the city. The contrast between a high level of education and a low level of political rights was particularly great in Aarau, and the city refused to send troops to defend the Bernese border. By Mid-March 1798 Aarau was occupied by French troops. On 22 March 1798 Aarau was declared the capital