Yongcheng was the capital city of the Qin State from the Spring and Autumn Period (770-476BC) to the mid Warring States Period (476-221BC). It remained the capital of the Qin from 677-383BC.

Covering an area of 11 square kilometers, the city was orderly arranged with interlacing streets. To date, three large-scale palace areas were discovered at the site. The No 1 temple constructions comprise the main gate, middle court, ancestral temple, the Zhao Temple, the Mu Temple and surrounding walls, covering an area of nearly 7,000 square meters. Its halls were all built on earth and wooden structures, with huge roofs. The site is the largest and best-preserved construction group of the period prior to the Qin Dynasty (221-206BC). The No 3 construction site covers an area of 21,800 square meters and comprises five palaces from south to north. It contains the most complete sleeping quarters of the period.

Covering an area of 21 square meters in the southwest of the city site is the mausoleum area of the Qin ruler where 43 large tombs and sacrificial pits were unearthed. The area has a standard layout that can be divided into 13 cemeteries. Excavations indicate that people of the Qin State had already formed a set of architectural concepts on the overall arrangement and design of the mausoleum. The - shaped tomb is the most superior, and other tombs are shaped like the character  or a knife handle. The largest tomb is the No 1 Tomb of King Qin -- so far the largest wooden coffin chamber discovered in China.

The No 1 Tomb has a coffin chamber 59.4 meters long from east to west and 38.5 meters wide from south to north, including a 240.6-meter-long path that covers an area of 400,000 square meters. Located in the middle of the coffin chamber is the main room, which is divided into front and back rooms. The front room represents the palace where King Qin discussed political affairs before his death; the back room represents the palace where he dined and slept. Over 600 cultural relics made of various materials, such as gold, jade, bronze, iron, bone, pottery, lacquerware and wooden cultural relics were found in the coffin chamber. Some relics, such as the golden woodpecker, white jade dagger and jade ornament resemble the jade horse head found in the Terracotta Warriors and Horses Pits of Qin Emperor Shihuang. They reflect the masterly crafts and well-developed techniques of the early Qin State.

Also unearthed at the Yongcheng Site were 67 large construction components made of bronze that reveal the unparalleled, luxurious style of Yongcheng Palace.