Granary/1.03

Empire
The Granary is a simple building that increases resource income rates and extends army limit / population cap. All this is done via its researches, which means if the building is lost, you'll still have these bonuses. The building is also pretty small and surprisingly sturdy for its size, but with everything it offers tied to researches, there is no need for it be be rebuilt once everything has been had. This therefore makes its small size and durability somewhat meaningless.

Unfortunately for the Empire, no one wants to trade with them, as such, they only have access to the first two Income researches, and they're also slightly more expensive than they are for the other races. But still, these skills are great and should be the first thing you aim for when hitting tier 2.