The town center is the most important building in a nation. If the town center falls as a result of war, then the nation is lost.
The town center provides a limited storage space for the five primary resources in the game: Food, Wood, Metal, Stone, and Gold. The storage capacity of the town center can be increased by upgrading the town center.
At the start of the game, the maximum level a town center may be upgraded to is level 3. Once the player has increased the level of their empire, they may increase the level of their town center, but never beyond the level of the empire.
The town center controls the number of buildings a nation may have. When your town center is level 1 to 3, your nation has 10 slots for buildings. When your town center is level 4 to 6, the nation will have 15 building slots. When your town center is level 7 to 9, the nation may hold 20 buildings, and finally when your town center is level 10, the nation will have 25 building slots.