The Deoksu Palace(Deoksugung ; 덕수궁, 德壽宮), is one of the five grand palaces of the Korean Joseon Dynasty.
When the Japanese invaded Joseon in 1592, King Seonjo escaped from Seoul and fled to Uiju. When the war was finished, he returned to Seoul. But there is no place that he stay, because all of the palaces(such as Gyeongbok Palace, Changdeok Palace, Changgyeong Palace) had been burned down during the war.
So, he lived in this place, which was originally the residence of Prince Wolsandaegun who was King Seongjong's elder brother, as a temporary palace.
King Gwanghaegun who succeed to King Seonjo renamed this palaces as Gyeongun Palace (Gyeongungung ; 경운궁). The palace became a secondary royal residence after the king moves to Changdeok Palace. And Queen Dowager Inmok was confined to the palace, and it was renamed West Palace(Seogung ; 서궁). After he was overthrown by King Injo, it was returned to their original owners.
After two years long refuge, King Gojong returned to power and he chose to reside in this palace. He renamed this palaces as Gyeongun Palace again. And Electrical system and fencing installed at the palace and the name of the palace was changed to Deoksugung Palace, meaning the palace of virtuous longevity. He remained at the palace even after he had relinquished the throne to his son, Emperor Yunghui (or Emperor Sunjong ; 융희제, 순종)
During from 1910 until 1945, when Korea is under the colonial rule of Japan, the palaces's buildings were destroyed and developed a public park.