Heunginjimun (Gate) was built by King Taejo during his fifth year of reign in 1398. It is designated as National Treasure of Korea No 1. The gate is more commonly known as Dongdaemun (Great East Gate), as it was the major eastern gate situated in the city walls (Seoul City Wall) built to protect Seoul during the Joseon Dynasty.
Designated Historic Site No. 10, Seoul City Wall is an 18.2 km wall that surrounds the city, built during the Joseon Dynasty. Along its length are four large gates and four small gates. The popular mountain ridge trail that follows along the well-preserved rampart commands spectacular panoramic views of midtown Seoul.