Complex sentence: The "Solituderennen" (eng: "Solitude race") events and the 11.4 km "Solitudering" near Stuttgart were named after the nearby Castle Solitude.
Split into simpler sentences: The "Solituderennen" (eng: "Solitude race") motorsport events are held on the 11.4 km "Solitudering" race track near Stuttgart. The event and the track were named after the nearby Castle Solitude.