What island in Denmark has 39% of the country's population and contains a mansion with an 8 hectare park?
Magleås: Magleås is a mansion in Høsterkøb near Birkerød in northern Zealand, Denmark. Magleås:  The mansion includes 8 hectare park, and borders on the Rude Forest ("Rude Skov"). Zealand: Zealand (Danish: "Sjælland" , ] ), at 7,031 km, is the largest (except Greenland) and most populated island in Denmark with a population of 2,267,659 (39% of Denmark's total as of January 2016).
Zealand