Aarau Castle

The core of the complex is a well-preserved, 25-meter-high medieval residential tower. It consists of limestone and stacked, roughly hewn boulders (megalithic masonry). Its square floor plan has a side length of 11.25 meters. The original masonry has been preserved up to a height of 17 meters. From the second floor upwards, the corners of the building show rough edge dressing. In the south wall, the windows of the second and third floors are in the late Gothic style. The top floor was added in 1790 and was originally plastered. It is topped by a hip roof from the same year.

On the north side of the Schlössli, a palas from the late 13th or early 14th century is attached. Its plinth floor has a similar wall thickness to the tower, while the two upper floors are significantly thinner. Above it rises a half-hip roof. Also from 1790 is the adjoining stair tower on the east side. It can be reached via a covered wooden bridge from the 19th century, which spans the former neck ditch.

The Schlössli houses the Aarau City Museum. It deals with the city's history, showcases crafts and living culture of past centuries, and also offers an exhibition on surveying instruments and photography. Individual rooms are dedicated to various Aarau personalities. In the immediate vicinity is the Haus zum Schlossgarten, which served as the seat of government of the Helvetic Republic in 1798.

According to dendrochronological investigations, the Schlössli was built shortly after 1236/37, and thus a few years before the founding of the city of Aarau by the Counts of Kyburg. It was possibly planned together with the city layout. Earlier investigations assumed an origin in the 11th century. After the extinction of the Kyburgers in 1263, the city and the castle, inhabited by ministerials, came under the rule of the Habsburgs. The first documented mention of the Schlössli as "the old tower" occurred in 1334. This designation served to distinguish it from the somewhat younger Rore Tower, which is now integrated into the town hall.

The inhabitants of the castle changed frequently. Until the middle of the 16th century, these were mostly knightly families, even after the conquest of Aargau by the Confederates in 1415. These included the Lords of Kienberg, the Lords of Heidegg, the ministerial family Sumer, and the Lords of Luternau. Later, the Schlössli served as a distinguished residence for various bourgeois families from Aarau, including the Schmuziger and the Hunziker. At the beginning of the 17th century, the superstructure of the palas was renewed and the tower was covered with a hip roof. The Bernese fortress builder Valentin Friderich carried out an interior renovation in 1624 and also had the masonry repaired.

The silk ribbon manufacturer Johann Rudolf Meyer acquired the Schlössli in 1790. He had it raised by the current top floor. A new roof and a staircase on the east side were added. In 1803, he established a dormitory for students of the Cantonal School in the Schlössli. In 1808, the castle came into the possession of the Herosé family, and in 1862, Colonel Emil Rothpletz acquired it. From his inheritance, it was donated to the municipality of Aarau in 1930. After a thorough renovation in 1931/32, the City Museum opened in 1939. In 1975/76, an extension was built southeast of the Schlössli to house a historic mill from Bözen. In 1978/80, the facades were renovated, in 2000 the roof was restored, and in 2003 the window reveals were restored. In 2006/07, the city commissioned a study for an expansion of the City Museum. The winning project by Diener & Diener envisages another new building on the west side.