Super Mario World/Donut Ghost House

To complete the House you have to go all the way to your right and take the door. Once on the other side, keep heading left and take the next door. If you hit the yellow block, a P-Switch will pop out. If the switch is pressed, a silver door will appear, which must not be taken. Wait until the Switch times out or avoid hitting the switch, then take the door again. Hit the yellow block and this time a vine will pop out. Take it and you'll find the exit.

There is a secret exit at the beginning of the level that you must fly up to at the far left top that will take you to the alternate exit. This alternate exit will open the path to the Top Secret Area.