What to do in Cairo on last day before flight home at 18:00

I'm going on an organised tour of Egypt later this year. On my final day, when there is nothing organised, I'll have a fair amount of time to fit something in as I fly home at 18.00 from the main airport.

I'll have done the pyramids and the GEM earlier in the trip. I'd love to hear from others what others feel would be the best use of time before heading to the airport. Whatever I do I'll be booking a guide to avoid the Cairo chaos and harassment.

Thanks!!