Map from the George Washington Memorial Parkway website.
If you look at the center of the page you will see a lighthouse icon. This is where Jones Point Lighthouse is located. Just south of I-95/I-495 on the west bank of the Potomac River. In Jones Point Park. (As construction finishes there could be detours in the area). Map made from AAA online TripTik.
If you look and see the pushpin (near the middle), you can see Washington D.C. and Maryland are just across the river. Map made from AAA online TripTik.
One more map, zoomed out to see most of the East Coast. Map from AAA online TripTik.