Sorgenfri Palace was built by the architect Francois Dieussart in 1705-06 for Carl Count Ahlefeldt. From 1730, this country house was owned by the royal family, and Crown Prince Frederik (V) had court architect Lauritz de Thurah build a wing for the gentlemen of the Court and a horse stable. When Frederik V became king, the palace was given to his aunt, grand duchess Sophie Caroline of East Friesland, who let de Thurah demolish the main building in 1756-57 and build a new palace. From 1791-94, the heir apparent, Frederik (VI), expanded and modernised the palace.
Frederik VII later transferred the palace to the state. In 1898, the state placed the palace at the disposal of Crown Prince Christian (X) after modern conveniences and a glassed veranda were installed. Sorgenfri Palace was Christian X and Queen Alexandrine’s preferred summer residence, and both Frederik IX and the heir presumptive, Prince Knud, were born there. Prince Knud and his wife, Princess Caroline-Mathilde, lived in the Palace until their deaths in 1976 and 1995, respectively. Sorgenfri Palace is not open to the public, but part of the park is accessible to the public.
References:Duino Castle was built by the Wallsee family in 1389 on the cliffs overlooking the Gulf of Trieste. It replaced an older castle from the 11th century. Over time, the Wallsee family disappeared and the castle, after having been used as a prison, became the residence of the Luogar and Hofer.
At the end of the 19th century it became the property of Prince Alexander von Thurn und Taxis from the Czech branch of the House of Thurn and Taxis. It remains with the family to this day with his great-grandson Prince Carlo Alessandro della Torre e Tasso, Duke of Castel Duino the current owner. The castle has been opened to the public as a museum and park.