This walled city dates back to 1430 and is the principal reason to visit Xingcheng. Under renovation, it's nonetheless an atmospheric place to spend a few hours, perhaps between dips in the sea.
In addition to the City Walls, the Drum Tower, which sits slap in the middle of the Old City with 360-degree views, and the watchtower, on the southeastern corner of the city, are all intact. You can do a complete circuit of the walls in around an hour.
The Old City is home to around 3000 people, with shops for daily life. Also inside the Old City is the Gao House, the former residence of General Gao Rulian, who is one of Xingcheng’s most famous sons. The impressive and well maintained Confucius Temple, built in 1430, is reputedly the oldest temple in northeastern China.
You can enter the Old City by any of four gates, but the easiest one to find is the South Gate (南门; Nánmén), which is just off Xinghai Nan Jie Duan at a large intersection. There are signs in English and Chinese pointing the way and maps at each gate. If you plan on seeing everything, buy the ¥100 pass that grants admission to every paid sight within the walled town.