Would this be considered homework ?
* Do not expect LQ members to do your homework - you will learn much more by doing it yourself.
If it's just 'Ideas' for a project, Then design a MAN for your local government connecting all their facilities (City Hall, Police, Fire, EMS, Municipal Courts, Water, Sewer, Ports, Building and Housing, Road Maintenance, Waste Management, Parks and Recreation, City Garage, etc..) using Fiber optics, VPN's and Point-to-Point connections (T1/E1), etc...
With this idea you can go as small or large as you desire because a local government has a LOT of separate facilities, but nothing says you have to connect everyone during 'phase one' of your project.
You need to take into account city wide IP addressing schemes, bandwidth needs, A single point Internet connection for the entire network to simplify security. Centralized DNS, and DHCP. etc..