From the World Heritage inscription:
In the early 15th century, the Emperor T’aejong ordered the construction of a new palace at an auspicious site. A Bureau of Palace Construction was set up to create the complex, consisting of a number of official and residential buildings set in a garden that was cleverly adapted to the uneven topography of the 58-ha site. The result is an exceptional example of Far Eastern palace architecture and design, blending harmoniously with the surrounding landscape.
The Changdeok Palace sits in central Seoul and is an intact, impressive former seat of the Korean monarchy. Unfortunately, the palace seems rather sterile because all of the artifacts and furnishings have been removed. It is a collection of mostly empty buildings. Unlike most World Heritage sites, you can’t just buy a ticket and stroll about the grounds. You have to be with a tour guide, and tours leave about every hour/half hour in different languages. Tours last about an hour.