The Zytglogge tower is a landmark medieval tower in Bern, Switzerland. Built in the early 13th century, it has served the city as guard tower, prison, clock tower, centre of urban life and civic memorial.The Zytglogge is one of Bern's most recognisable symbols and, with its 15th-century astronomical clock, a major tourist attraction. It is a heritage site of national significance,[1] and part of the Old City of Bern, a UNESCO World Cultural Heritage site.