The next one is the Horniman Museum, admittedly it's a bit out of town, but it's worth making a day trip for. There's so much to do, the ground is beautiful with the view of London in the background, there are animals like llamas, goats, rabbits and also a Robot Zoo exhibition on at the moment which was fun (scroll right to see C and his friend dressed as chameleons yesterday). There's a small aquarium downstairs as well.