It would have a big dock for storing many of the visitors' spaceships. Each white key would be an entrance, because it has to provide many entrance points due to the high amount of spaceships traffic before and after each event.
Any graphical contribution would be helpful: before any design there should be an artistic representation. This is a grandpiano with texture of spaceship, where people sit below the open lid, inside the spaceship, enjoying the event while watching the artists and stars.
The lid would be an excellent surface for installing Open solar sunshine flower cells, because in order to let people see the stars, it is better that they are facing to the opposite direction of the closest star. This way while the event takes place, the open lid would provide energy to the spaceship while it is absorbing sunlight, providing a comfortable shadow for improving the spectators' experience :D