A non-invasive archaeological investigation was carried out using Real Time Kinematic (RTK) topographical survey on the AD 10th to 13th century Kujindui site in Northeast China. The examination of previous documentation and satellite photographs shows the lack of precision on the knowledge of this medieval site. The RTK measurement provided data to draw a topographical contour map and a 3D digital model that reveal the outline of the enclosure wall. It allows defensive architectural features to be reconstructed. The precisely geolocated plan provides the basis for future research and preservation. In October and November 2013, a joint team from the Jilin Province Archaeology Institute and the Cultural Institute of the Nong'an 农安 District carried out a salvage excavation on a gas pipeline between Harbin 哈 尔 滨 and Shenyang 沈阳, in Northeast China, outside of the Kujindui 库金堆 site. Located northeast of the town of Helong 合隆, west of the Yitong 伊通 River and north of its east-west running tributary, the Kujindui site is near the modern village of Chengzili 城 子 里 (Figure 1; Guojia Wenwuju 1993: 41). It is surrounded by a large number of contemporary medieval settlements, most of them attributed to the "Liao-Jin" period. The Liao 辽 Dynasty (AD 907-1125) ruled Mongolia (today both the Mongolia Republic and Inner Mongolia Province in the PRC), a part of eastern Russia, and Northeast China (often called Manchuria). The Jin 金 Dynasty (1115-1234) took control over this region during the 10th to 13th centuries. This whole period is often called "Liao-Jin" in Chinese history. A walled settlement had been previously described at Kujindui as: An irregular square, oriented 30°, the east wall measuring 345 m, the west wall 330 m, the south wall 360 m, and the north wall 340 m, for a total perimeter of 1,345 m. The wall is built of rammed earth, the foundation of the south wall is preserved to a height of 5 m, only a height of 1 m exists for the west wall, and only fragments can be seen of the north and east walls. On each side there are three evenly spaced observation terraces: these are not very clear on the northern and eastern sides, but very distinct on the southern and western sides. The terraces have a top diameter of 2.5 m and a 10 m diameter at their base. There is a gate at the centres of the east and west walls, of 20 m width. Each of the four corners had a tower; the northeast and southwest ones are relatively well preserved, 3 m across at the top, 25 m across at the bottom, and 3.5 m in height. The northwest and southeast towers are only preserved 1 m above the ground level. Outside of the south wall, on the east and west sides, there is a terrace linking to each tower, the side of each measuring 10 m at the top, and 20 m at the foundation. Nowadays the eastern one is not visible any more, but the western one is well preserved (JSWB 1987: 136).