Blink and you'll miss it, but Chrono Trigger actually showed what the inside of the 1999 domes was like pre-apocalypse. It's in one of the secret endings; you

Blink and you'll miss it, but Chrono Trigger actually showed what the inside of the 1999 domes was like pre-apocalypse. It's in one of the secret endings; you can see it here starting around 4:10: https://www.youtube.com/watch?v=5WR0AmpABjk https://www.youtube.com/watch?v=5WR0AmpABjk