Beijing City Fortifications - Outer City

Outer City

The Outer city was also called "Guocheng" or "Waiguo". It was expanded in 1553. The walls were 7.5 to 8 metres high, and were 12 metres wide at the bottom and 9 metres wide at the top. The southeastern corner was built on the diagonal to avoid low swamps in the area. This fulfilled the legend of Nüwa mending the heavens: the heavens were missing in the northwest and the earth was sinking in the southeast.

The southern walls encompassed the southern walls of the Temple of Heaven, and the eastern and western walls were parallel with the Inner city's walls, about 2 kilometres away. This was where the rammed earth walls of the Yuan city of Dadu had been located before being abandoned in the closing years of the Hongwu era (1368–1398) during the early Ming dynasty. Walls in the northeastern and northwestern sections were built using materials recovered from the Yuan rammed earth structure. The Outer city walls had a perimeter of approximately 28 kilometres. The entire enclosure of the inner and outer cities formed a "凸" shape with a perimeter of 60 kilometres. Eleven gates were built, three each on the eastern, southern, and western walls, and two on the northern walls (one on the northeastern section and one on the northwestern section).

When the expansion of the Outer city was being planned in 1550, one idea called for nine small minor cities to be built around the nine Inner city gates, which would have been a formidable addition to the city defenses. Construction began in 1550 on three of these minor cities. However, because of the proximity to the Inner city gates, where many commoner's houses and shops had sprung up, many buildings needed to be dismantled. The disgruntled commoners forced the abandonment of the project not long after construction began. In 1553, it was decided that the remaining rammed earth walls of the Yuan city of Dadu would be dismantled and the raw materials used to complete the Outer city walls to form a "回": a square within a square. The plan called for the Outer city walls to have a perimeter of 70 kilometres. The east and west walls would have been 17 kilometres and the north and south 18 kilometres. The plan called for 11 more gates, 176 more enemy sight towers, two additional sluice gates outside of Xizhimen and Tonghui River, and eight more sluice gates at other low swampy areas. The Outer city expansion was a grand project, greater than any of the capitals of the previous Chinese dynasties. The Emperor approved, and construction began in 1554. Under the supervision of Yan Song, the project was divided into segments. The southern walls were built first to add extra defenses for the bustling commercial district south of the Inner city gate at Zhengyangmen. The eastern and western walls were planned for the second segment of the project. However, due to successive invasions from the Mongols and Manchus, soldiers were called away to the northern frontiers to defend the Great Wall, and thus few could be spared for construction. A great section of the Forbidden city caught fire in 1557, and workers and funding were funnelled towards repairs and reconstruction of the palaces. The expansion of the Outer city walls was thus never completed. In 1564, the barbicans of the Outer city gates were built.