They are beautiful (and I've never actually been in one where worshipers were present. Always just these incredibly bright, inviting—but empty—spaces).

Have you ever managed to see any activity in one? I've only ever found them like this. They are always literally and figuratively cool. Incredible visual chill going on and about 10C cooler than outside, somehow.

The Cao Đài temples definitely do not. They are very colorful. Lots of blues, oranges, yellows. I'll post some exterior photos tomorrow, maybe.