Go ahead...build!!!Are you in Miletus? Unemployement is good. Very good. With unemployement you can build anything you want! First, expand your industry to the fullest (weapons, pottery, furniture, marble,wine, oil). This will make you rack in the $$$$. As well, don't forget that as houses get bigger they require a lot more food so you will need to add farms. If you still have unemployement after that build more clay pits/furniture workshops to supply your people with pottery and furniture once they reach insulae level.
Ok, done all that and still have unemployement! Well, if you are in a military scenario, build tons of walls and towers everywhere. This will quickly eliminate some unemployment.
Still have unemployement. Man you sure had a lot! Build a palace block. This will take up about 400 workers and will boost your prosperity sky high as well as your tax dollars!
If you have done everything you can and still have unemployemnet: just build tons of culture structures or hospitals (academies and hospitals are always useful and they take up 30 workers each) or other structures.
If you are on the verge of desperation just delete some housing.
Trust me your problem will never get that far! Soon enough you will be begging to have unemployement!
Hope this helped. GOOD LUCK!!!