The Hall was initially available at L21 but that changed with an update in Sept 2016. It is now available for purchase at L33. You will need Carpenter's Kits to begin production Building Tips:
Check Neighbors for a Large Library. These will drop Knowledge each time!
Any level Mine on your land or at Neighbors can drop Copper Nuggets, they can also be crafted in the Laboratory
You will need a Lumber Mill upgraded to L3 for Poles to make Glass, Poles can sometimes drop from any level Lumber Mill at neighbors but they are very rare. It is faster & easier to run your own Lumber Mill
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The Hall timer was reduced from 6h to 3h with a May 2017 update