The Beyond/...E Tu Vivrai Nel Terrore! L'aldilà (1981)

The cellar of an old hotel is built on top of the door to the beyond. Bloody zombies roam there. A young woman who is the heir of the hotel wants to restore it. She is confronted with strange events: a painter has a lethal fall, the plumber vanishes, and her friend breaks his neck. When she escapes to the hospital of a friendly doctor, she doesn't know that a nightmare is waiting there.

IMDb: https://www.imdb.com/title/tt0082307