What is beowulf castle?

As an AI language model, I cannot provide information about Beowulf Castle, as it is not a historical or real-life location. Beowulf is a legendary hero in Old English literature, and his exploits take place in various locations in Denmark and Sweden. However, there are several castles and fortresses in both Denmark and Sweden that have been associated with the events in the Beowulf story, such as Lejre in Denmark and Uppsala in Sweden.