The structure of Bern's city centre is largely medieval and has been recognised by UNESCO as a Cultural World Heritage Site. Perhaps its most famous sight is the ''Zytglogge'' (Bernese German for "Time Bell"), an elaborate medieval clock tower with moving puppets. It also has an impressive 15th century Gothic cathedral, the ''Münster'', and a 15th-century town hall. Thanks to  of arcades, the old town boasts one of the longest covered shopping promenades in Europe.