Complex sentence: The house began to slip into dilapidation soon after the public fascination and abuse began, and was slowly torn apart, although it wasn't until 1923, when efforts to restore the manor were beginning, that the house would be vandalized and set ablaze.
Split into simpler sentences: The house began to slip into dilapidation soon after the public fascination and abuse began, and was slowly torn apart. It wasn't until 1923, when efforts to restore the manor were beginning, that the house was vandalized and set ablaze.