The Zytglogge (Bernese German: ; ) 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. Despite the many redecorations and renovations it has undergone in its 800 years of existence, the Zytglogge is one of Bern's most recognisable symbols and the oldest monument of the city, and with its 15th-century astronomical clock, a major tourist attraction. It is a heritage site of national significance, and part of the Old City of Bern, a UNESCO World Cultural Heritage site. History When it was built around 1218–1220, the Zytglogge served as the gate tower of Bern's western fortifications. These were erected after the city's first westward expansion following its de facto independence from the Empire. At that time, the Zytglogge was a squat building of only in height. When the rapid growth of the city and the further expansion of the fortifications (up to the Käfigturm) relegated the tower to second-line status at around 1270–1275, it was heightened by to overlook the surrounding houses. Only after the city's western defences were extended again in 1344–1346 up to the now-destroyed Christoffelturm, the Zytglogge was converted to a women's prison, notably housing Pfaffendirnen – "priests' whores", women convicted of sexual relations with clerics. At this time, the Zytglogge also received its first slanted roof. In the great fire of 1405, the tower burnt out completely. It suffered severe structural damage that required thorough repairs, which were not complete until after the last restoration in 1983. The prison cells were abandoned and a clock was first installed above the gate in the early 15th century, probably including a simple astronomical clock and musical mechanism. This clock, together with the great bell cast in 1405, gave the Zytglogge its name, which in Bernese German means "time bell". In the late 15th century, the Zytglogge and the other Bernese gate towers were extended and decorated after the Burgundian Romantic fashion. The Zytglogge received a new lantern (including the metal bellman visible today), four decorative corner towerlets, heraldic decorations and probably its stair tower. The astronomical clock was extended to its current state. In 1527–30, the clockwork was completely rebuilt by Kaspar Brunner, and the gateway was overarched to provide a secure foundation for the heavy machinery. The Zytglogge's exterior was repainted by Gotthard Ringgli