What is the Tanoby Ruins in Pokemon LeafGreen?

Question

And all the Chambers? Whats In Them? They Were empty when I checked..

Answer 1

You have to complete a puzzle on Seven Island first. Then when you go back you can catch Unown there, each chamber has different Unown symbols/letters.

http://www.serebii.net/red_green/unown.shtml