Complex sentence: Frankenstein Castle (German: Burg Frankenstein) is a real hilltop castle in the Odenwald, overlooking the city of Darmstadt, and allegedly an inspiration for Mary Shelley when she wrote her monster novel Frankenstein.
Split into simpler sentences: Frankenstein Castle (German: Burg Frankenstein) is a real hilltop castle in the Odenwald overlooking the city of Darmstadt. Allegedly this castle was an inspiration for Mary Shelley when she wrote her monster novel Frankenstein.