The musical notes are hidden throughout the Garden of the Sphinx. You will need to find all 12 notes to open the locked entrance.
Step 2: Play the notes
Once you have found all of the notes, you need to play them in the correct order. You can find a guide that shows you the order of the notes here.
Step 3: Press the buttons
After you have played the notes, you need to press the buttons on the door in the correct order. The buttons are located above the door.
Step 4: Enter the cave
Once you have pressed the buttons, the door will open and you will be able to enter the cave.
Note: You will need to use different items to open different locked doors.