On the tour . lunch may be included. On many tours you will be dropped off near a restaurant and given some free time to eat, shop, and do sightseeing on your own. Most tours will also make stops at local markets for you to buy local handicrafts and souvenirs.
Depending on the size of the city there may be more then one company giving tours. Choose the tour that has a brochure you like also make sure that you guide speaks your language or that there is a translation service . if you can't understand your guide, you will have a bad day.