After dynastic quarrels however, there was a Norman conquest in 1072. Normans conquered Palermo after a long siege. Indeed, the feat proved difficult because the Normans had never besieged such a populous city with such powerful walls. After 5 months siege, Normans built numerous stairs and war machines and finally conquered the city. The family who returned the city to Christianity were called the Hautevilles, including Robert Guiscard and his army, who is regarded as a hero by the natives. It was under his nephew Roger II of Sicily that Norman holdings in Sicily and the southern part of the Italian Peninsula were promoted from the County of Sicily into the Kingdom of Sicily. The kingdom's capital was Palermo, with the King's Court held at the Palazzo dei Normanni. Much construction was undertaken during this period, such as the building of Palermo Cathedral. The Kingdom of Sicily became one of the wealthiest states in Europe.