Changdeokgung Palace, one of the “Five Grand Palaces” of the Joseon era, is a large palace and UNESCO World Heritage Site in downtown Seoul. For sightseeing purposes, the palace has been divided into two: the main palace and the stunning Huwon garden (also known as “The Secret Garden”) at the rear. First built in 1405 by King Taejong, the palace was the longest-serving royal residential palace. Although now, sadly, only about 30 percent of the buildings it once contained remain. The Secret Garden is well worth visiting while at the palace, especially during the autumn when the gardens are at their most colorful.