"Accommodates travellers who will work for the colony. The colonists in the surrounding area will enjoy the tavern and generate more gold. In addition, you can hire mercenaries who stay at the inn."
Inn provides 100 workers, at a cost of 100 food and 50 energy (which is as twice food-effective as houses, and be the same energy-effective as tents). Instead of costing gold, it consumes 30 wood per 8 hours to maintain.
It also buff dwellings gold generation by +10% within an 52x52 area (within 24 blocks radius). This effect stacks with the effect of Bank and The Victorious.
Mercenary units can be hired every 5 days. Some are veteran soldier center units at higher gold cost. Others are engineering center units that require more gold but no iron or oil, except for upkeep. The inn even allows you to recruit units you have not researched yet.
The population of houses boosted around the Inn is known as Prestige. As the population within the Inn's radius increases, more and better mercenaries will be available.
You can check the Prestige and how many days left till new mercenaries arrive in its infomation.
You need to have at least 200 colonists in your colony to build the inn.
Just like wonders, you can only build one Inn in your colony.
In the campaign: