Changdeokgung is the best preserved of Seoul's five grand Joseon-dynasty palaces and a UNESCO World Heritage Site since 1997. Built in 1405, it served as the primary royal residence for about 270 years. The palace is notable for the way its buildings follow the natural contours of the landscape rather than imposing a rigid grid — a contrast to the more formal Gyeongbokgung nearby.
The real highlight is the Huwon, the "Secret Garden" at the back of the complex. This 78-acre wooded garden has lotus ponds, pavilions, and centuries-old trees. Guided tours of the garden run several times daily and last about 90 minutes — book ahead during spring and autumn when the foliage draws big crowds.
The main palace grounds can be explored freely, but the garden requires a separate ticket and guided tour. Entry is around 3,000 won for the palace, 5,000 won extra for the garden. The nearest subway stop is Anguk Station (Line 3), exit 3.