The Palace of Time
The Palace of Time is a secretive underground installation, the office of the minister of calendars. Its location is shown on no map. From behind a guarded entrance in the Palastfeld, a spiral stair leads to a stone corridor and a tiny square room, no bigger than the bedroom in a cheap boarding house. The plain but watertight stonework suggests that this may once have been a Dwarf installation.
Rumour has it that Sigmar himself instituted the office of minister of calendars, to log all the various festivals of different cultural groups in the Empire. In Sigmar's day, keeping track of various tribal celebrations was a difficult diplomatic necessity. These days, the increasing diversity of communities in the Empire makes the job even harder, just as their degree of cooperation makes it less important.
The minister of calendars also has a secondary role, to act as an early warning to the Sigmarite Cult of any evidence suggesting that a particular festival might involve forbidden rites or heretical messages. The current minister of calendars is an elderly man called Gaspar von Derberg. He spends most of his days in the office, passing through his ledgers, making updates, and interviewing the agents that he sends throughout the Empire to report the details of local festivals and traditions.