Board Thread:Dragon City Gameplay Questions & Answers/@comment-8744057-20140412125124/@comment-27403314-20140425113410

Me too, it's the same as a normal breeding place, but added with the availability to breed a certain dragon normally unbreedable at other breeding places.

So, to get a certain dragon you want in the list, for example: Deep Red Dragon, then you'll have to upgrade your sanctuary to lvl 1, then only can it be available to be bred there, but remember that you can only breed them there too, not at other breeding places.

To upgrade again for other dragons, you have to buy a certain number of steps using money, or maybe skip the whole process with gems.

Hopefully this helps. :)