Kaiseraugst (Swiss German: Chhäiseraugscht) is a municipality in the district of Rheinfelden in the canton of Aargau in Switzerland.

It is named after the Ancient Roman city of Augusta Raurica whose ruins are nearby.

The prefix Kaiser- ("imperial") refers to the fact that from medieval times the town formed part of the Habsburg territory of Further Austria, as opposed to the neighbouring village of Augst, which was part of the Canton of Basel in the Old Swiss Confederacy.

About AD 300, following the loss of the Limes Germanicus and the right bank of the Rhine, the Roman army built a fort near the city of Augusta Raurica.

The fort, which was named Castrum Rauracense, was intended to serve as the headquarters of the legio I Martia and to protect a ford over the Rhine.

Emperors Constantius II and Julian assembled their armies at the Castrum Rauracense before marching to battle against the Alemanni.

[3] Following the collapse of the Roman Empire the fort remained occupied as local Germanic tribes moved in.

[4] In 894 the East Francian King Arnulf granted the church in Kaiseraugst to his vassal Anno.

[5] In the early 1960s, the Kaiseraugst nuclear power plant construction project was met with strong opposition from the population, who occupied the site in 1975.

After the Chernobyl disaster, the Swiss government and Kaiseraugst Nuclear Energy AG agreed to abandon the project.

[12] About 28.1% of the total households were owner occupied, or in other words did not pay rent (though they may have a mortgage or a rent-to-own agreement).

[10] The historical population is given in the following table:[4] The Roman city of Augusta Raurica with the Castrum Rauracense fort is listed as a Swiss heritage site of national significance.

[16] The entire village of Kaiseraugst is designated as part of the Inventory of Swiss Heritage Sites.