I Opened a Door in My Garage Ceiling and There's a GIANT Room Up There

I've lived in my house for two years, and I never thought about what was over my garage. There's an access point in the ceiling with a little door, and I always figured it was a tiny crawl space or something. Today, though, I finally got a ladder tall enough to reach the access door. I went through, and I was amazed by what I found up there!