You can have two or three main water shut-off valves. First is the curb stop, usually near the sidewalk-street and located in a Buffalo or B Box. Second, next to the indoor water meter, you may have one shut off valve or one on each side of the meter.
Your piping responsibility.
City service starts at the curb valve. You are responsible from the curb valve to the water meter. City is responsible for the inside meter. You are responsible for all indoor piping. Keeping your plumbing system maintained prevents headaches. Contact one of the oldest area plumbers for advice and help.
Main water shut off valve maintenance.
If you have a newer ball valve (teflon coated), it does not need maintenance. If you have an older gate valve you should turn it on-off a few times to prevent corrosion and keep it functioning well in the event of an emergency.