Some of the older corporation stops have a lid like that, turn it 90° and the lid should come off exposing the old shut off valve. Seen them a lot in places line housing Co-ops and low income housing as a way to keep the average joe out of there.
This is what you need to take off the nut. They are very common in the northern suburbs of Chicago. Once you get it off, you need a round way key which is a rod that goes into the round way that grabs the corp. the handle on the key should be pointing towards the house indicating the water is on. By giving it a quarter turn making the key point perpendicular with the road tells you it's off. Good luck!