Where the old road to Halmstad crosses the Lagan River lies the ruins of Lagaholm Castle. Lagaholm Castle was built in the 13th century and demolished in the 17th century by order of Charles XI. At that time, the fortress served as a defensive fortress. The ruins were excavated and restored in the 1930s. Sydkraft's operations center, salmon farm, and power plant are now located in the area. Sydkraft's exhibition and slideshow provide a historical overview of Lagaholm's importance in the Middle Ages as a border crossing between Sweden and Denmark.