Mystery Hole in Driveway?

I have owned my home in the southern part of IL for about 35 years. It has a concrete driveway that runs from the street straight into the garage. In roughly the center of the driveway a square hole about 18 x 18" was cut and then neatly refilled with concrete (this was before I bought the house). I have always wondered why that hole was cut and what is under it, if anything. I doubt that it's Jimmy Hoffa. If any of you good folks have had occasion to cut such a hole in a driveway perhaps you could shed some light on this mini-mystery. The house was only about 3 years old when I moved in. Cheers!