The small town on the Rhine was already important in ancient times as a transit route between the two banks of the river. Its oldest parts (the fortified Seglingen bridgehead on the right bank) probably date back to the 11th century, while the actual town on the left bank is said to have been built in the 13th century under the local Lords of Tengen.
In 1496 Eglisau was sold to Zurich and was the seat of the Zurich bailiffs until the former Confederation was dissolved. The construction of the Rheinfelden power station caused the water level of the Rhine to rise as far as the houses facing the river, so the bridge had to be transported from the church area to E on the western outskirts. There is evidence of Neolithic and Roman settlements, but to a modest extent. On the Rhine stood watchtowers on the limes, erected under the emperor Valentinian (364-375). At the end of the 11th century the barons of Tengen built a tower to defend the ferry on the left bank of the Rhine. There is no record of the founding of the town with its bridge between 1238 and 1253. The town, which essentially consists of two long streets (the Untergasse and the Obergasse), retains numerous Renaissance and Baroque facade elements. Evangelical parish church, baroque building from 1716-17, is connected to the Gothic choir of the previous church (1350 ça.). The interior design (three-nave hall, side galleries on wooden pillars) is reminiscent of St. Peter's Church in Zurich. The choir has late Gothic frescoes (c. 1490, attributed to Hans Fischer and Hans Ott).