Celestial Secret Valley was established by the Scholar of Secrets several hundred years ago...
As the years passed for hundreds of years, the surrounding terrain remained unchanged, yet the buildings within the valley were all perfectly intact.
Chu Qing discovered that this was because all of the buildings in the valley were constructed from stone.
They can withstand the erosion of wind and rain and the wear of time.
It is also for this reason that the Scholar of Secrets had arranged an Absolute Array that remained effective even after hundreds of years.
The dilemma for Chu Qing was that he originally intended to set fire to Celestial Secret Tower, thus resolving the threat of Yellow Springs Powder.
But now, if the Celestial Secret Tower was also made entirely of stone, how could he start a fire?
Moreover, traces of mechanisms could be seen everywhere between the pavilions and buildings.
These mechanisms were not particularly deadly, just as Sang Qing had said.
