Rosie O'Donnell's ditching her sweet mansion on Miami's Star Island -- and based on these pics ... we can't understand why she'd ever leave.
As we told you last week, Rosie just put the pad on the market -- asking price $19.5 million -- and it includes waterfront views and a massive aquarium in the dining room.
If you're one of the Mega Millions winners -- feast your eyes on these shots around the 11,000 sq. foot spread ... it could all be yours!
If you didn't win ... check out the gallery anyway. Dream a little.