The castle was built in 1605/06 by the Blarer of Wartensee family. This family was originally from St. Gallen and had become wealthy from the linen trade. One line of the family settled in
Wartensee Castle at
Rorschach, hence the name of this line. With the election of Jacob Christoph Blarer of Wartensee in 1575 to the
canons of the
cathedral of Basel the family gained interests in the Basel region. Jacob Christoph Blarer was also one of the main leaders of the
Counter-Reformation in Birseck. The Blarers began to expand their power in the Basel region when Jacob Christoph Blarer appointed his brother Wolfgang Dietrich Blarer to the upper
Vogt of
Pfeffingen in 1583. This position gave the family a steady source of income from
tithes, taxes and interest. Many other privileges, for example a charter granted by Jacob Christoph Blarer in 1604, led to a steady growth of wealth of the Blarer family. In the years before his death in 1608, he tasked his nephew Wilhelm Blarer, to consolidate the family's position and power by building a castle at Aesch. In 1607, the castle grounds and surrounding property were given to Wilhelm by Jacob Christoph. At the same time, Jacob Christoph as the
Bishop of Basel freed Wilhelm from all offerings. By 1702, the
Prince-Bishop allowed the Vogt Johann Konrad Blarer to live in the castle at Aesch rather than in Pfeffingen, but his clerk had to stay in
Pfeffingen Castle. As the castle at Pfeffingen lacked the comfort and prestige that the family desired for a family seat, in 1740 the Blarers moved their center of power into Aesch. During the
Thirty Years' War the castle was damaged, but was rebuilt immediately. At the time of the
French Revolution a hospital was set up in the castle. Finally, in 1851 the castle was bought from the family by the municipality of Aesch and rebuilt. Two classrooms and two teachers' houses were added. It was renovated in 1900 by Rudolf Sandreuter, who moved the main entrance to the village side and added
gothic revival and an additional half-round tower. Starting in 1909 it was used as a school and community center. Since the renovation of 1958/59, which restored its original condition, the municipal administration has occupied the castle. ==Castle site==