Jiumenkou Great Wall used to link with Shanhaiguan Great Wall. It is the only Great Wall which was built above a river, JiuJiangHe (Jiu River). Locals used to say "The Wall runs above the river, and the river goes through the Wall." Although largely rebuilt, it is still a marvelous sight.
Jiumenkou became a UNESCO site in 2002.
Jiumenkou Great Wall was first built in North Qi Dynasty (479-502 AD) as its very strategic location. Like most other existing Great Wall sections, currently only the Ming Dynasty section still exists. In 1644 there was an important battle (YiPianShi Battle 一片石大战) happened in Jiumenkou, which ultimately leaded to the replacement of Ming Dynasty by Qing Dyansty.
Jiumenkou Great Wall belongs to Huludao City, Liaoning. From there one needs to hire a private transportation to the Great Wall. Most visitors come from Shanhaiguan, as it can easily be combined in a one day trip. A oneway taxi by meter from Shanhaiguan to Jiumenkou is about 40-50 RMB (July 2015). Some take cheaper illegal licenseless tuktuk, and it is on the passangers' own risk.
In between Shanhaiguan and Jiumenkou there is also Jiaoshan Great Wall 角山长城 (30 RMB). If one is a Great Wall fan, he will need at least 1.5 days for the three Great Wall sections.
80 RMB for entrance fee. Keep the entrance ticket as you will need it later.
Besides the Great Wall, remember to check the Ming Great Wall Tunnel, which can be found no where else on the planet. The Tunnel is 1027 meters' long and could provide transportation and accomendation for 2000 soliders. To get to the entrance of the tunnel, one needs to walk pass a bird park and a lot vendors.
There are a lot of vendors around for noodles, snacks, fruits, drinks.
Shanhaiguan and Jiaoshan Great Wall can be the next destinations for Great Wall fans.