Yup! Pre-Canterlot Equestria? Thats my concept of The Ancient castle of the Royal sisters or whatever it was called
This idea hit me when I was re-watching FiM pilot for no parent reason whatsoever. I'm guessing Everfree forest wasn't that big back then or the ruins were actually on the other side of it. It was just my silly guessing. I will be very unhappy if they show this castle fully intact in season 4.
Lots of happy colours in this one. Even my *.psd file was actually named colorfulland!