at various times as a youth growing up in Minnesota, our family lived in three different houses that shared a particular design feature. In each case there was a glass block set in the concrete entry slab. it provided some light for the small space beneath it, an approximately 4x4 ft area accessible from the basement. that's where the pump for the water well head was located, keeping it accessible yet out of the way and safe from freezing. don't know if that was a standard arrangement or not, but for us it sure was.