Claim: Massi is best known for Maasilinna Castle (German: Soneburg), which in Medieval times served as the center of Eastern Saaremaa and Muhu,It was established in 1345 by Livonian Order' Landmeister Burchard von Dreileben after the complete quelling of the St. Maasi_sentence_10 George's Night Uprising.
Evidence: Maasi is best known for Maasilinna Castle (German: Soneburg), which in Medieval times served as the centre of Eastern Saaremaa and Muhu.