...and your question is...?

It would be great to clean it up and restore it!

No question at all! Just sharing some of the more interesting things you find peeling back the layers! Tile on the main bathroom floor wasn't half as interesting but definitely not a shape found today.

I haven't seen those shapes in a midcentury tile.

It would be nice to preserve some of them in some way.

That looks like Korean Porcelain Mosaics. back in the mid- 80's it was as common as glass tile is now.

Cool! I've done wallpaper archeology, but never flooring.
You now have higher ceilings.

Thanks Bill! I knew someone would have seen it before. I really like it but I do not like that amount of grout on my bathroom floor. I haven't made any effort to clean it up but I think the grout was put down approximately that color. That is the same color as the 4X4 wall tiles in the 60" shower.

Grout color can always be changed with colorant, if that's the problem