大湾遗址位于皇华城内城东部腹心地带，经考古揭示，确认为一组大规模院落建筑。据形制结构分析，大湾遗址的性质功能应为与“咸淳府故治”有关的衙署区。该院落基址坐北朝南，中轴线清晰，依地势分布于5级台地上，由南向北逐层抬高。
第一级台地以面阔七间、进深四间为核心，柱础石作精致，有覆盆宝莲华、覆盆牡丹华、转角莲华等形制。主殿西侧附碑石亭，现存石碑座三个，可与《蜀中名胜记》所载《宋忠州贡院碑》《金鱼堡碑》《升忠州为咸淳府碑》对应。
第二级台地在院落中轴线上发现连接一二级台地工字殿，工字殿东、西侧为天井及石砌方台，北侧为大型台基建筑包边墙。
第三级台地因后期扰动保存较差。
第四级台地中部发现主体建筑龟头屋，东西对称分布两个方形水池，包含大量废弃筒、板瓦及勾栏望柱等建筑构件，西侧廊庑、厢房局部保留方砖墁地。
第五级台地发现大型台基包边墙，中部附小型月台，轴线上为规整石阶踏道。五级台地包边墙与四级台地建筑散水间形成排水沟，石板铺地，东接水池，向西延伸以暗沟形式排出台地。
The Dawan Site is located at the core area of the eastern part of Huanghua City and confirmed through archaeological excavations to be a large complex of courtyard buildings. According to analysis of its architectural structure, the nature and function of Dawan Site should be government offices related to "Xianchun Prefecture's former administration." The courtyard is situated with its foundation at a north-south orientation, following a clear central axis. It is distributed on terraces of five levels, gradually rising from south to north according to the terrain.
The first-level terrace has a width of seven bays and a depth of four bays as its core component. The column base stones are exquisitely crafted, with various decorative patterns such as "lotus flower on the reversed bowl", "peony flower on the reversed bowl", and "corner lotus flower". A pavilion with stone steles is situated at the west side of the main hall, with three remaining stele bases at present. These bases can be related to the " Stele in Zhongzhou Examination Hall of Song Dynasty”, "Jinyu Fortress Stele," and "Stele for the Promotion of Zhongzhou to Xianchun Prefecture" mentioned in the "Records of Famous Places in Shuzhong (Sichuan) Region".
A hall shaped like the Chinese character “工” was discovered on the second-level terrace along the central axis of the courtyard. It connects the terraces of the first and the second level. There are patios and stone-paved square platforms on the east and west sides of the hall, as well as a large stylobate and walls with edge covering on the north side.
The third-level terrace is poorly preserved due to later disturbances.
In the central part of the fourth-level terrace, the main building known as "turtle head house" was discovered. It features two square pools which are symmetrically distributed in the east and the west, along with many discarded tubes, pantiles, and architectural components such as carved balustrades and baluster columns. In the west are corridor buildings and wing rooms which have partially retained square brick floors.
On the fifth-level terrace, a large stylobate and walls with edge covering were discovered, with a small platform attached in the middle and a well-arranged stone step pathway along the axis. Between the walls with edge covering on the fifth-level terrace and the building apron on the fourth-level terrace, drainage channels are formed, and stone slabs are paved on the ground. The terrace is connected to a water pool in the east and extending westward to drain off water through underground drains.
