The so-called Roman Treaty regulates cooperation between the three cantons of Basel-Landschaft, Aargau and Basel-Stadt in relation to the important Roman city of Augusta Raurica. The aim of the treaty is to jointly preserve and research the ancient site and the Kaiseraugst fort and make it accessible to the public.

The treaty was drawn up in 1975 between the cantons, the Pro Augusta Raurica Foundation and the Historical and Antiquarian Society of Basel. It regulates in particular the cooperation and division of tasks between the cantons of Basel-Landschaft and Aargau and stipulates, among other things:

• The canton of Basel-Landschaft coordinates the archaeological work in Augst (BL) and Kaiseraugst (AG).
• The cantons of Basel-Landschaft and Aargau carry out archaeological excavations on their respective cantonal territories.
• The ruins of the ancient city are managed and maintained in a uniform manner.
• The canton of Basel-Landschaft is responsible for restoring, conserving and maintaining all finds.
• The canton of Basel-Landschaft is responsible for mediation and public relations.

This treaty remains a model of successful cross-cantonal cooperation to this day, serving an important piece of national cultural heritage.