Super Mario 64/Tower of the Wing Cap
The level is basically composed of five towers: four small ones and a large one. On top of the large one, you will find the button that activates the red cap blocks.
 Collect 8 red coins
The eight red coins are placed in pairs in the air around the towers. Fly round and round to get them. Press Z if you don't get both of them in one run. If you don't you can't get the star. You will need to use the wing cap to collect them. One pair is so high up in the air that you can't land before you collect them. You should jump on the red switch first so, if you miss, you can come back later.