The Guest and Banquet House from 1750 is also called the Murder Castle, as it is where Claes Fredrik Horn from Huvudsta Gård, Jacob Johan Anckarström, Adolph Ribbing, Carl Pontus Lilliehorn and Carl Fredrik Pechlin planned the assassination of Gustav III. It used to stand where the current Huvudsta Gård and conference center stands (see the full story here https://reveal.world/story/from-conspiracy-to-conference ) and  relocated to its current location in 1834. Today, it serves as a daycare centre and is also available for event rentals.