TIL how Běijīng ("North Capital") could previously (well, one of the previous times) have been Zhōngdū ("Middle Capital"). Sounds obvious, there must have been some other capitals in at least two directions, but I never looked up what those cities were.
The summer capital of Shàngdū (Xanadu! Yes! That one!) ("Upper Capital") was north of it, in today's Inner Mongolia.
In contrast to my assumption above though, there doesn't seem to have been a Lower Capital at the time. There was a Xiàdū during the Yan dynasty in the Warring States Period, but that's over 1000 years earlier, so that must have been lower than something else.
*looks it up*
Xiàdū was below Ji, which was the main capital of the Yan kingdom. That was *also* yet another name for Beijing. Beijing must be a *really* good place for a Chinese capital, huh.
en.wikipedia.org/wiki/Zhongdu (中都)