|The Nimbian aptitude for complex mechanics is simply unsurpassed" - Nimbian Mechanic.|
Workshops build the Units of battle. Each workshop can only build a few units, and they must be aligned with the workshop, so choose carefully. Unfortunately, if a Workshop is destroyed you will loose the ability to build anything that Workshop was currently producing, until you build another workshop to replace it.
The sun workshop is able to put into production units aligned to sun, as well as Generators for any of the three furies of Wind, Rain and Thunder. This means it is often useful when used in conjunction with a workshop for the other three furies, as you can free up production slots in the other workshops by using the sun workshop to put the generator in production.