The city ai recommends a ton of workers early on. It is great when the city is growing fast, but when the city population starts to stagnate, I get stuck with a lot of workers. Now with this other question telling me not to build roads between cities smaller than 6 population, I don't see much use for a lot of workers so after a few hundred of turns (epic speed), they all get fortified until cities grows.
Is there something special to do with them actively? For example in Civilization 4, whenever a worker was mining, it had a slight chance of finding a ressource so you could just build/clear mines with hopes of finding something useful.
Best Answer
First of all, you can just sell them if you don't need them. Not only do you immediately get some gold, you also decrease the number of units you own, and units cost gold each turn.
Secondly, connecting a city to the capital by railroads greatly increases a city's production, so if you can afford it it's recommended.
Finally, you can replace improvements you don't need / want with other improvements. For instance, for cities that are big enough it's probably better to replace farms with mines or trading posts.
You can set your workers to "automate", and they will automatically build roads, replace them with railroads if available, and will replace improvements with other improvements the AI thinks you need more.