Pyeongyang Castle is an old capital city of Koguryo, surrounded by Moranbong Hill standing tall in the heart of Pyeongyang. Pyeongyang Castle is a castle that combines the strengths of mountain fortresses and of flatland castles. It is designed to defend the capital city and the people's properties and houses effectively against enemy attacks. Its Inner Castle, Northern Castle, Middle Castle, Outer Castle, gate sites, and building sites are still preserved. The letters inscribed on castle stones discovered within the Inner Castle indicate that Pyeongyang Castle is a castle town built during the Koguryo period.