We were driving through our city to eat at a restaurant when we noticed a bright ball of light hovering over a central monument, Liberty Memorial. We were curious and drove toward this part of town, only a 5 minute drive to reach this monument. We got there and the object began to move NW at a slow stall and unusually low altitude. It became a jet. It flew low enough for us to see in detail the underbelly with no markings, all white non-commercial jet making no sound. Our car did not vibrate as expected to be directly under a jet. I watched as the jet slowly passed over our windshield and then looked at it through the moon roof briefly. We were driving 25 mph. The scale was 2/3 the space of our moon roof. It took approximately 3 seconds to cross the moon roof view. It kept up its NW flight path with a constant speed and altitude. We only lost sight because we went to our destination.