You've probably plopped this building a long time ago, but there are many upgrades you can get for this building so it probably deserves it's own section here as it is the focal point of all your govenemental activities and a place where you can see some of the problems in your City by clicking on some of the protesters which are usually gathered outside and trying to do something about their issues.
Plus - do you actually need to add all of those Government departments in every City? Possibly not...
As you progress through the game and your city grows and grows at various milestones you will be awarded with an Upgrade to City Hall. These cost about 15,000 Simoleans to add and cost a further 500 Simoleans hourly to maintain. They useful, yes, but you don't need to add them all in every city in the same region and the benefits don't just apply to your city but all Cities in the same region.
The upgrades you can have are outlined below, and remember if one of these are added in a City, the upgrade effectively applies to all Cities in the same region, all cost 15,000 Simoleans each initially and 500 Simoleans hourly to run.
Department of Education
With the Department of Eduction you have the ability to add High Schools and Universties two essential block in the overall eduction system of your City and especially essential if you are pursuing research projects for The Great Works or improvements such as a Solar Power Array.
Department of Finance
This basically just gives you the ability to set tax rates independently according to low medium and high wealth residents, commerce, and industry, so instead of having three tax rate options, you have nine. Great for adding an extra percentage of tax to the richer Sims in your neighbourhood. Once you've added a Department of Finance to one City in a region the benefits apply to all cities in the same region.
Department of Safety
This department offers you improved police, fire and health service options. You'll be able to build a police precinct, hospital and large fire station, all of which offer upgrades and improvements that are not possible with the standard version of each of those services.
Department of Culture
With this department activated in a City in your region you have access to a few new large parks, a whole host of landmark buildings and pro stadiums. Great if you want to attract a larger number of tourists to your City who will bring the Simoleans to spend in your commerce zones and sleep in your hotels.
Department of Utilities
You can build a water pumping station, sewage treatment plant and a recycling center with this department. All essential buildings, so you'll need one of these departments somewhere.
Department of Transportation
Here you can make various upgrades to your mass transit options such as a municipal bus station, ferry port, and a municipal airport. This department basically facilitates easier transport between cities in the same region as well as improving your transport options for Sims within your own City.