Sapaca Castle, locally known as Sapaca Kalesi, lies on a hill above the village with the same name, in the province of Erzurum in Turkey.
I was not able to find any information about this castle. So, if you know more please mail me.
When I visited, I wasn't able to find a path to the castle, although the elderly villagers told me there was one and it would only be a 10 minutes walk to the castle. Instead I had a nice talk and several glasses of tea with them. Too bad, it looks nice.