The courtyard retains its original design from Super Mario 64.

The courtyard can be accessed by talking to a Toad behind Peach's castle while wearing the Super Mario 64 costume. In Super Mario Odyssey the castle courtyard returns as an Easter egg containing 2 power stars (acting as a Power Moon) one for opening several chest in a specific order and the other for using cappy on the eternal star statue. Luigi's is on the upper alcove (do a backflip spin) and Wario's one is over the fountain, near the two signs. Also one of Luigi's and Wario's rabbits can be found in the courtyard. Slide into 'Princes Secret Slide' in less than 21 seconds down and there will appear another star. At the bottom in a block there is a star. On the base floor, enter the door at the top left.

Also in the DS version, there 3 brick blocks, which takes you to The Secret Of Battle Fort course, which is accessible only if you are Mario, Luigi, or Wario, as Yoshi cannot destroy brick blocks. How to get all the 15 castle secret stars.

Killing it will result you get access to the fifth level, Big Boo's Haunt. When you have no stars, there's nothing, after a Star, a Boo will be in the hallway and group of regular-sized boos will appear in the courtyard (In the DS version hitting Boos with 8 red coins gives you a secret star), and after 12 stars (15 in the remake) a Big Boo will be in the hallway and also appear in the courtyard. Castle Courtyard (also called Castle Gardens) is in the back of Princess Peach's Castle in the games Super Mario 64 and Super Mario 64 DS.

Mario 64 castle secret stars