Bonusy

Of course the great buildings aren't just a waste of space, but grant powerful bonuses that grow with the building's level. Depending on the building, you might get the following:

Military boost Raises the attack and defense bonus for units in attacking army, adds up with every building

Fierce resistance Raises the attack and defense bonus for units in defending army and increases support pool bonus, adds up with every building

Coin boost Raises the outcome of your houses up to 90 times with each collect, adds up with productivity and motivation

Supply boost Raises the outcome of your production buildings, adds up with productivity, motivation, and other supply boosts.

Good Production Produces a certain amount of goods from your current age every 24 hours. From Modern Era on, produces double the amount in unrefined goods.

Medal production Produces a certain amount of medals every 24 hours

Research Produces a small amount of forge points every 24 hours

Coin production Produces a certain amount of coins every 24 hours

Supply production Produces a certain amount of supplies every 24 hours

Population Permanent population bonus

Happiness Permanent happiness bonus

Quest reward boost Raises only your coins, supplies, goods, medals, or diamonds from quest rewards.

Penal Unit Recruits unattached units every 24 hours, randomly chosen from any military building in your city.

Guild Goods Produces current era goods which go straight to the Guild Treasury.

Support Pool Bonus Raises your guild's support pool bonus, adds up with every building

Aid Goods Produces 1 random good when aiding another player's city (manually motivating/polishing them also counts as aiding). The age of the random good corresponds to the age of the building you are aiding.

Plunder Goods Produces random goods for up to 3 neighbors with each collect when plundering another player's city. The age of the random goods corresponds to the age of the building you are plundering.

Contribution Boost Raises the Forge Points, Medals, and Blueprints you receive from donation rewards.

Aid Blueprints Raises the chance of obtaining a blueprint when aiding another player's city (manually motivating/polishing them also counts as aiding). I.E. Having a 100% bonus will double your chance of finding a blueprint