This annual, free event is always held the Saturday after the weekend of 4th of July, with a raindate of that Sunday (fireworks only). It is a huge celebration of the founding of the City of Alexandria.
Stretching between Fairfax, Pendleton, and Madison Streets in Old Town Alexandria, the Celebration is free and features a performance by the Alexandria Symphony Orchestra, children's activities, community group displays, etc. Bring your lawn chairs, picnic food and coolers. Some vendors sell hot food and glow necklaces/toys, and portable toilets are available. The event usually starts around 4 pm and culminates with a fireworks display over the Potomac River. The fireworks usually start at 9:30 pm and last about a half an hour.
The one problem with the fireworks is that the flight path for airplanes landing at Ronald Reagan National Airport is directly over the launching area, so the fireworks are stopped periodically while planes come through. It kind of stops the momentum of the fireworks building up to a grand finale. But, the kids will enjoy seeing the planes so close up, and, for a free event, this is quite fun. A nice family activity!