The construction started in 1077 by Archbishop Gebhard V. Helffenstein to protect his 'interests' from the ruling Emperor Heinrich IV. The succession of Archbishops that followed continued to live in the fortress, expanding as they went until finally finishing it in 1681. The end result is a mix of styles and construction techniques. The Archbishops had already moved to the less militant looking Residenz in 1595. The fortress is considered the largest completely preserved castle in Europe and the Bergmuseum contains displays of medieaval torture instruments and artworks. The Rainermuseum houses armoury exhibitions. Access is either a long walk up the hill or the Festungsbahn funicular, behind the St Peterskirche, it runs every 10mins, 9am-9pm; fortress open daily Oct-Mar 9.30am-5pm, Apr-Sep 9am-6pm, admission only €3.60, admission, guided tour and funicular €12.