If you are American, I suggest you visit this Memorial Garden. It is a short walk, ending at the small photo museum. If you have mobility problems, you will still probably not have trouble.
Inside the gate, you wind through a path which has an assortment of wreckage from the time the building was blown up by terrorists in 1998. Part of the vehicle which housed the bomb is in a sculpture at the end.
Inside the photo museum are pictures which I certainly never saw before going there. Viewing them really brings home the tragedy of that horrific act.
Many Kenyans remember that day too. The bombing was planned on one of the busiest corners, and at one of the busiest times of the day. One of my friends lost hearing in one ear for 3 weeks after the blast.
Sometimes it seems a little strange that the side of the memorial park is used for public functions, but there is usually a meeting or memorial of some kind going on during the day. You can also bring a picnic and sit on the grass.