The Site of Yan Xiadu is located between the north Yishui River and central Yishui River, 2.5 kilometers southeast to Yixian County in Hebei Province.

After Western Zhou conquered Shang, King Wu enfeoffed north Yan to Shao whose son set up a state during King Cheng's reign with the capital at Ji (today's Beijing), known as Yan Shangdu. Later, the Yan State moved its capital to the riverside of the Yishui River, known as Xiadu. In the mid Warring States Period (475-221BC), King Zhao of Yan renovated the capital, bringing a flourishing time to the city. After Yan was conquered by Qin in 222BC, the city was abandoned. 

Under the leadership of renowned archaeologist Ma Heng, a research team excavated the site in 1930. A comprehensive excavation was carried out by Hebei provincial cultural relic research team in 1961 that removed the veil of the Site of Yan Xiadu.

Taking a rectangular shape, the city site was 8 kilometers from east to west, and 4 kilometers from south to north, comprised of the eastern and western cities with a wall in between as the division. The Xiadu was the largest city in the Warring States Period.

With rich cultural relics, the eastern part of Xiadu city had five districts, respectively for the palace, workshops, residential area, graveyards and rivers. The palace area, located in the northeast of the city, comprised of three groups of constructions. The main palace building, Wuyangtai, was situated in the center of the area. Built with tamped earth, the two-storeyed building was 140 meters long from east to west, 110 meters wide from south to north, and 11 meters high. Featuring in high tamped-earth foundation, the palace buildings reflected the large scale of city construction in the Warring States Period as well as the highly developed economy and culture. Workshops circled around the palace area, while the residential area scattered in the southwest and northeast parts of the city. In the northwest of the city was the burial ground, which was divided into Jiunütai and Xuliangzhong. Tombs of lords and nobilities were arranged in proper orders according to their positions. In an excavation in 1965, a large number of valuable cultural relics were unearthed in one of the tombs.

The eastern part of the city ruins is well preserved, with visible outline of the city walls. In resent years, many construction materials were unearthed in the city, such as beast-head pottery pipelines and tiles, which were made with craft. The western part was mainly for defensive purposes with fewer relics remained than that of the eastern part.

A number of historic sites scattered around the Yan Xiadu, such as the Golden Platform in Jintai Village of Yixian County. Legend has it that the Golden Platform was built by King Zhao of the Yan State to attract talent people over the state. Poets and scholars left numerous poems there. Dating back to 2200 years ago, Prince Dan of Yan saw Jing Ke off at the riverside of the Yishui River. Jing Ke, who undertook the heroic task of assassinating Qin Emperor Shihuang, sang a solemn tune that still lingering over the riverside. The lyric went like this, the wind is whistling while the Yishui River is cold, a hero will never return once he sets off. The solemn and stirring story of Jing Ke was passed on from generation to generation.

About 2.5 kilometers southwest to Yixian County is Jingshan Mountain where stands a 13-storeyed octagonal tower named Jing Ke Tower with a multi-eave roof. Around the mountain are some historic sites, including the Jing Ke Hall, Jing Ke Cenotaph, and stone tablet in Jing Ke's hometown.