Guonei

Guonei (in Chinese) or Gungnae (in Korean) City was a second capital of the ancient Korean kingdom of Goguryeo located in Manchuria. The perimeter of its outer fortress measures 2,686m.

History
Guonei was chosen to become the capital city by the kingdom's second ruler, King Yuri during the 10th month of the year 3 AD. The city was sacked several times until the rise of the 19th ruler, Gwanggaeto the Great, who greatly expanded Goguryeo's territory and made it a formidable power in northeast Asia. When King Gwanggaeto died in 413, his son, King Jangsu, inherited the throne and moved the capital down to Pyongyang in 427. The city played a central role of the kingdom after the power transfer.

Just before the fall of Goguryeo, Guonei City fell to the Silla-Tang Chinese alliance when General Yeon Namsaeng, son of Yeon Gaesomun, surrendered the city in 666. Goguryeo fell in 668 when the Tang army captured Pyongyang and took King Bojang and Yeon Namgeon into custody.

UNESCO World Heritage Site
Guonei is part of the UNESCO World Heritage Site Capital Cities and Tombs of the Ancient Koguryo Kingdom, together with nearby Wandu Mountain City and the Wunü Mountain City, in modern northeast China.