In 1372, craftsmen in Liaoyang began building a rammed-earth city to secure the Ming dynasty’s frontier. Seven years later, the commander Pan Jing expanded it eastward by one li, built a northern wall to house surrendered ethnic minorities, and divided the urban area into a southern city of about 4.5 square kilometers and a northern city of about 1 square kilometer. Over more than forty years, craftsmen encased the rammed-earth cores of the walls with uniformly laid, pressure-resistant blue bricks and sealed them with durable mortar joints. By 141? the main southern city wall was 10 high and about 8 kilometers in circumference.

The wall was built for heavy movement and defense. Its base tapered upward to a flat, seven-meter-wide summit, wide enough for carriages to pass each other. Four corner watchtowers guarded the horizon: Choubian in the southeast, Zhenyuan in the northeast, Wangjing in the southwest, and Pinghu in the northwest. At the East Gate, known as Pingyi Gate, a 2,700-square-meter barbican system stood ready. Its curved outer wall was designed to trap invaders in a tight space, supported by internal troop quarters, grain stores, and stone drainage channels.

Power shifted over the centuries. Nurhaci's Later Jin forces captured the city in 1621 and made it their capital in 1622, before building Tokyo Castle. Natural erosion slowly wore down the battlements. In the mid-1930s, Japanese occupying forces demolished the East Gate watchtower and its barbican, burying the foundations under residential neighborhoods.

The buried past reemerged in June 2011. Workers digging an underground parking garage on Dongda Street struck three curved brick foundations, revealing the lost East Gate barbican. Today, visitors can walk through the Ming City Wall Ruins Park in Baita District, where a 50-meter-long section of the central partition wall stands consolidated at 7.5 meters high. On December 31, 2024, the reconstructed Pinghu Tower officially opened on the original northwest corner foundations. Inside, a glass walkway allows visitors to look directly down at the original Ming-era stones, bridging the gap between modern footsteps and medieval defense.