An Empire in UE is a group of players that work together.
Empires are ranked against one another by points scored against bosses and by win/loss ratio in empire wars. Empires are grouped into tiers for the purposes of matching for empire wars.
Members can donate cash, Concrete Blocks and Steel Beams towards various upgrades. Players are limited to a single item donation per day, and there is also a daily cash donation limit which can be raised by purchasing the HQ upgrade or by having Victoria Vanderbilt.
When first formed, an empire can have 50 members. This can be increased by purchasing the HQ Leadership upgrade.
Other upgrades (all in HQ) that help outside empire wars are: