Assuming you have chosen a nice venue for the special occasion, be sure to include photos of it. If it is a restaurant, include photos of the sign. In several years, the look of the restaurant will probably change and the memory will help set the stage for your event. If you are having the event in someone's house, they will probably move in time and having a photo of the venue will be a nice memory. Take a photo as well of something identifying whose house it is. If they have a nameplate on their door or a street sign that might work. Alternatively, you could make a sign with their name and address. Take a photo of some of the cars too. They will change in look over time.