Nice story and photos, thanks for sharing. Most important thing for astronomers of old times was to mark positions physically, for example that when solstice is etc.
By doing so ( keep in mind that, while the Universe is not static it feels static unless one keeps tracking astronomical objects for longer periods of time, generations) they surely make their own astronomical life much easier. There were no computers and by marking positions on the sky of most easily noticed objects all changes could be spotted more easily.
Hence the opening points, structure characteristics etc. You got the point there too it seems.

One event was magnificent and people who were watching the sky back then were blessed by it and most likely there was a 'tea party' in this observatory when SN 1054 took place. I envy them :)