Pinyin: Jiù fēng shān
English: Vulture peak mountain
Coordinates: 40°18'58"N 118°6'23"E
Text: "Here lies the Great Wall built by the State Yan (one of seven states of the Warring States period), and its narrowest section is only 70 centimeters, which can be called the narrowest Great Wall." - Jiufengshan
So it turns out another name for this Great Wall is Duanyu (断欲), as it was listed on the Jiufengshan map.
I went here last week. It's located in Zunhua, only 18km away from the bus station. There is no public transportation to getting there, so I took a taxi for 35 kuai. Ticket for Jiufengshan is 50 kuai.
Photo album: http://imgur.com/a/MJlgl
I didn't find the 70cm 'narrowest Great Wall' that was mentioned in the tourist book. Or maybe I did and just didn't notice, hah. This Great Wall is different from a lot of the other sections I've seen in Tangshan – it's mostly just boulders and rocks stacked atop each other.