Bonuses

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.

Relic Hunt This ability gives you the possibility to receive Relics on the Guild Expedition map whenever you successfully solve an encounter. Relics are very valuable and can appear in 3 different rarities. Each level increases the chance to find a Relic but also the odds to find an uncommon or rare Relic, as opposed to a common one.

Critical Hit Gives all units the chance of dealing 1.5 times the expected damage when attacking units of the same era. Critical hit also works against Reactive Armor (if expected damage is 4-4, a critical hit will do 6-6 damage). Rogues (and other no-age units) are not affected/cannot use this ability until they transform into another unit. A critical hit doing at least 11 damage will one-hit kill any unit, even with the morale bonus. This bonus applies to all attacking armies plus your defending army in PvP. The critical hit will not happen when a unit is retaliating.

Helping Hands Gives you a certain chance to get a random resource when aiding another player's city (manually motivating/polishing them also counts as aiding). You can recieve goods from your current age, supplies, coins, medals, or even Diamonds.