Ludwig's Thump Castle Hotel
From the Super Mario Wiki
Ludwig's Thump Castle Hotel, labeled Ludwig's Castle Hotel on its entrance, is the fifth hotel found in Hotel Mario, owned by Ludwig von Koopa. The name is based off of the real-life Trump Towers, which are a series of hotels run by Donald Trump. It is a horror themed castle. Enemies found in there, were Skeleton Koopas, Boo Buddies, Big Boos and Pat the Bats. There are also vanishing doors to be found in the hotel, though if Mario finds Bowser's Ghost Cologne, he will be able to stop them from vanishing. The boss stage is known as Ludwig's Frantic Lab.