challenge: What was the original purpose of Špilberk Castle when its construction began in the 13th century?
  
  A. A major royal castle and the seat of the Moravian margraves
  B. Barracks for the Austrian military
  C. A fortress to protect the city of Brno from invaders
  D. A huge baroque citadel and the harshest prison in the Austrian Empire
  Answer: 