Wher are the solaceon ruins?

There are no 'Solaceon Ruins' as such.
There is only the Unown cave/tunnel.
If it is how you get there, the here's how:
Go to the north-east of the town, above the last house on the right will be a pathway. Go through there. Don't jump down the first or sencond ledge, jump the third.
You will see a cave--go towards there and enter it.

Hope I helped,
Reconiscool

Go above the top house on the left. There will be a trail. Take the trail all the way to the right. You will see a place to jump down. Jump down the ridge and you will notice a door to your right. Go in it and there you are.

Tell me you're kidding...

So obviously it's in SOLACEON Town, hence SOLACEON Ruins... Go to the northeast corner of Solaceon Town and go all the way to the right until you hit an end. Go down like 2 ledges until you can continue more to the right and into a cave. In any other room besides the main room (the room you're in now) you'll run into a lot of Unown. Also, in some of the rocks there, I think you can find a super repel, escape rope, and something else. But at the end, you find a rare candy, full incense, nugget and another item.

East of Solaceon Town. That is about all the detail you need

The 'Solaceon Ruins' are Located outside of Solaceon city near the top head left and there will be alot of trees go through them and you will find a cave entrance.