Kaiseraugst (Swiss German: Chäiseraugscht) is a municipality within the district of Rheinfelden in the canton of Aargau in Switzerland. It is named for the Ancient Roman city of Augusta Raurica whose ruins are situated nearby. The prefix Kaiser- ("imperial") refers to the fact that from medieval times this town formed part of the Habsburg territory of Further Austria, as opposed to neighbouring village of Augst, part of the then Canton of Basel in the Old Swiss Confederacy. Wikipedia