Hillhurst Mansion is a haunted house in Charterville. The previous owner was Old Man Hillhurst, who seemed to have died in the early 1900s based on his attire. It is here that Flabber and his fellow monsters live.
Since the monsters have taken up residence here, secret passageways have appeared, often used during the chase scenes, so any guests may ellude the monsters.
Flabber takes up residence in the Parlor, which is often where he meets with the Beetleborgs to discuss strategy. Otherwise, it's where they look for him for assistance with their daily lives.
The Entrance Hall has several ways leading out of it, including secret pasages, a moving wall that blocks one of the doors and so on.
Count Fangula, Frankie, Mums and Wolfie take up residence in the bedrooms/closests that have fallen into dissuse. The attic is the only safe place in the house as the only way up to it is a rope ladder; this proved useful when Art Fortunes needed a place to keep from being eaten by the monsters.
Due to a Magnavor monster playing the trumpet non-stop in the cemetery, Old Man Hillhust rose from the grave and began haunting the place (a bit redundant) to chase the monsters inhabiting it out, in order to get back his old place, so to have peace and quiet. The Beetleborgs stopped the monster and presented a trumpet to him as proof that the cemetery would be quiet again.