was characteristic for 15th-century astronomical clocks; all later such clocks use a northern projection. This would seem to confirm the dating of the clock to the 1405 or 1467/83 renovations. A clock is documented in this tower since 1405, when a new bell was installed. Interior The Zytglogge's internal layout has changed over time to reflect the tower's change of purpose from guard tower to city prison to clock tower. The thirteenth-century guard tower was not much more than a hollow shell of walls that was open towards the city in the east. Only in the fourteenth century was a layer of four storeys inserted. The rooms above the clockwork mechanism were used by the city administration for various purposes up until the late 20th century, including as archives, storerooms, as a firehose magazine and even as an air raid shelter. The interior was frequently remodelled in a careless, even vandalistic fashion; for instance, all but three of the original wooden beams supporting the intermediate floors were destroyed. Since 1979, the tower's interior is empty again and only accessible in the course of guided tours. References Bibliography External links Zeitglockenturm Bern Official Website in English and German Zytglogge Bern Flash 3D Panorama Tourist information by Bern Tourism Source texts relating to the Zytglogge on www.g26.ch Daily audio/video timelapse of the Zytglogge Buildings and structures completed in 1220 Old City (Bern) Astronomical clocks in Switzerland Horology Monuments and memorials in Switzerland Tourist attractions in Bern Cultural property of national significance in the canton of Bern Buildings and structures in Bern Clock towers in Switzerland