Understanding Beijing's historic axis line

With no online search possible at that time, I would look closely at any street maps I could find while also searching through the shelves at Beijing Foreign Languages Bookstore on Wangfujing. Gradually my thoughts started to coalesce about how historic Beijing was constructed around a master plan that envisaged a central axis line at its heart. Again I started appreciating the character 中 (zhong) and whether the vertical stroke could be a central axis with the frame representing China. I was also coming upon this concept in some academic writing. As I looked closely at historic maps, it became apparent how the early city had been laid out to follow this in many ways.

Beijing for me was like slowly reading and turning over the pages of a book to discover more.

I realized how physical geography helped explain some of its early history and construction. Looking north, a relatively narrow range of mountains marks the border, indeed an interface between fertile, arable lands to the south with much drier terrain beyond. The Great Wall acted as a defensive barrier between the two. The northern lands, initially grasslands giving way to deserts such as the Gobi, were inhabited mainly by semi-nomadic pastoralists. To the south, more humid conditions created the possibility of arable cultivation and ultimately an urban-based society. Several of the world's oldest cities are in China.

The Great Wall, a mainly Ming Dynasty (1368-1664) defensive structure, stood against incursions from the north. However, long before the Wall was constructed, the threat of invasion was real. Hence the massive walls and moats that were constructed around urban settlements such as Beijing.