Complex sentence: Later the Reuß, a ruling German family, built 2 castles in Greiz: the "Oberes Schloß" (Upper castle) and the "Unteres Schloß" (Lower castle).
Split into simpler sentences: Later the Reuß, a ruling German family, built 2 castles in Greiz. The "Oberes Schloß" (Upper castle) and the "Unteres Schloß" (Lower castle).