Instead of having a double work rate, which was mistakenly mentioned before, what if the staggered rate that TCs and Docks have applied to castles as well?
This would work to enhance the existing bonus.
This change could potentially give the Persians a slight buff, making them more viable on various maps.
It would make Conscription and trebs quicker to make, and give their early Imperial Age a better chance against other civs with better power spikes.
It would also improve all-in Castle Age strategies such as Kamandaran or War Eles.
The Persian Castle is already not very strong (missing Bracer), and to balance this, removing Hoardings, Architecture etc.
might be necessary.
However, it is unclear how this change would interact with Kasbah.