It's a Ghost House with Cosmic Mario! He appears after the first Boo. This is the Ghost House where the floor appears when you approach. I died from trying to get the first Star Coin.
Take 2- See Take 1.
Take 3- See Take 1.
Take 4- We get the first and second Star Coins. The second Star Coin moves until it's on the platform with lots of Boos. The middle item block there has a Starman, so we can defeat the Boos and Cosmic Mario. Of course, that doesn't stop him from reappearing after a while. We go to the upper right corner for an orange Mystery Box. We got the third Star Coin, over the floor near the wall, and fell.
Take 5- I got the first Star Coin and fell.
Take 6- See Take 5.
Take 7- See Take 5.
Take 8- I got the first Star Coin and ran into Cosmic Mario.
Take 9- See Take 4.
Take 10- We get all three Star Coins, reach the door, and the flagpole.