Cloud City 4-23 is the twenty-third level of Cloud City. To pass this level with three stars, you should pop all pigs and score at least 67,000 points.
Launch Lando when the fan is moving to the rightmost position. Shoot the chain (do not hit the TNT) to bring down two TNT. The fan will blow two TNT to detonate both structures. But you need a massive amount of luck to succeed this work.