Royal Restorations (RR) are special crafting resources and you can find your available RRs under the Elvenar icon on your UI.
They are used to upgrade event and crafted buildings and can be either earned from Weekly Tournaments, crafted in the Magic Academy with Blueprints (and/or Diamonds), won in events through the Royal Pass system, created by a Sorcerer's Hut premium building, or from the late-game Ancient Wonder Oracle of Fortune.
In my experience there are never enough, and I look forward to more ways to earn them (wink, wink, nudge, nudge
@helya)