Krummturm, Medieval defensive tower in Solothurn, Switzerland

Krummturm is a pentagonal tower near the Aare River with uneven interior levels connected by wooden staircases. The floors lead down to a roughly 10-meter-deep dungeon beneath the structure.

Construction likely began around 1454, prompted by the threat of an Armagnac attack near Solothurn's territory, and the tower was completed in 1462/63. A chronicle by Franz Haffner records that contemporaries nicknamed it "Kumuff" (roughly "barely up") because of the slow progress, caused by building difficulties and the city's strained finances after large land purchases in 1458. In 1947 the town council granted the tower to the Solothurn Artillery Association for 99 years; after renovation it opened as a clubhouse and artillery museum in autumn 1948.

The tower's nickname "Kumuff", roughly "barely up", recorded by chronicler Franz Haffner, mocked the slow progress of its 15th-century construction. Since 1948 it has housed the Solothurn artillery association's club rooms and artillery museum, opened to visitors at the association's 75th anniversary.

The tower is reached on foot from Solothurn's old town, its northeast base facing the old town and its northwest side toward the Aare. Inside, simple wooden stairs link the ground floor and the three upper floors, which differ in height. The ground floor is 3.8 metres high, the first floor 3.6 metres and the second 4.6 metres. The tower was opened for visits in autumn 1948.

The tower's nickname "Kumuff" (roughly "barely up") came from its slow construction: begun around 1454, it was finished only in 1462/63. In 1458 the city bought large territories around Olten and Gösgen, which likely left little money for building materials and craftsmen. Since 1947 the tower has been leased to the Solothurn artillery association for 99 years.