Municipal buildings do not provide a direct profit, but are necessary for the growth and development of any town. Constructing these buildings provides permanent reputation bonuses. Details for city buildings can be found in the following articles:
Roads improve the sanitation level of a town, reducing the chances and duration of plague outbreaks. More roads need to be developed with each new house or workshop that are built in the city.
Ideally, 80-100% of the roads should always be developed. There are concerns that developing roads reduces the available space for constructing buildings, but this is not entirely true. Roads may have a small impact if you try to pack buildings as tightly as possible (known as the "Turkish Building Technique"), but in a regular game this is not an issue.
Wells improve the hygiene levels, and help with fire prevention (there is a random Fire event).
Hospital and Chapel
These buildings reduce the chances and decrease the duration of plague outbreaks (plague event can last from a few days to a few weeks). They can be built after the town walls have been upgraded at least once.
Mint will encourage more rich citizens to settle in the town (50% increase), useful if you want to sell more luxury goods such as skins.
School will attract more beggars (30% increase), useful in towns with many production facilities.