source: palace sign
Deoksugung began as the palace of a 15th century Joseon prince. It became the king's official residence during the Imjin War (1592), when the other palaces had been destroyed, but after Changdeokgung was rebuilt in 1618 the Deoksugung reverted to auxiliary status. The palace was only named "Deoksugung" in 1909, when it became the residence of retired emperor Gojong; prior to that, it had gone by several other names. Gojong's residence, the Seokjojeon (see map), was the first modern palace building in Korea, giving Deoksugung an interesting mixture of modern and traditional buildings. Like other palaces in Seoul, it was heavily damaged during the Japanese occupation and later restored. For more information, see Deoksugung's official website including The Past and Present of Deoksugung.
Deoksugung consists of three palace compounds (focused on Hamnyeongjeon, Junghwajeon, and Seokjojeon respectively) that open off in sequence from a "main street" that extends west and north from Daehanmun. This is in contrast to the front-to-back axis of more traditional palace complexes like Changdeokgung and especially Gyeongbokgung. Deoksugung's plan is more like a "comb" rather than a "branch," if I may put it that way. Its mixture of the modern and the traditional presents a fascinating study in the evolution of Korean architecture.
Compared to the vast size of their prototype in the Forbidden City, these Korean palace compounds are constructed to human scale. The Korean palaces were designed to be inhabited by human beings, not immortals.