https://youtu.be/S2B0toDBlSI?t=1388

I happened to be on a bit of a Halo lore kick today. and watched this video
>each Halo ring has it's own unique theme
>the main theme for CE is the theme for installation 04/Alpha Halo
>installation 05/Delta Halo from Halo 2 also had it's own theme

Actually really cool.