The Huangyaguan section of the Great Wall of China runs along the ridgeline of Jixian County's rolling, verdant mountains. From the Huangya gate, the wall runs east toward Taipingzhai and west toward Wangmaoding Mountain. Both sections can be hiked in a few hours, providing gorgeous views. This section of the wall was restored within the last few decades, and it offers a taste of everything Great Wall visits can offer: incredible natural views and hiking, military and cultural history sites (there are several garrison locations and military fortifications along this section), and ease of access. While it's a little far afield from central Tianjin (a two-hour bus trip), it's worth making. The crowds are less dense than at sites closer to Beijing, and the setting far more picturesque. (In the fall, hikers can admire the season's fiery red foliage in the valleys around the pass.)
Admission is ¥45-50, depending on the season, and transportation should be less than ¥100, including the regional bus from Tianjin and tourist mini-bus from the train station to the ticket office.