The Prague City Archives (Czech: Archiv hlavního města Prahy) is one of the departments of the Prague City Hall. It collects, preserves, processes and makes available archival materials documenting the historical development of Prague since the Middle Ages up to the present. Together with the National Archives of the Czech Republic the Prague City Archives is one of the largest and most important archives in Bohemia. It was established in 1851.
More information on the Wikipedia page 
The website is