Nairobi National Park is about 10km outside of Nairobi. Nairobi is a huge, bustling city but you can do some pretty good game viewing just outside the city. I did a four hour tour which picked me up at my hotel in Nairobi and then drove me to the park and around the different game trails. I saw several lion, giraffe, rhino, zebra, hippo, crocodile, wildebeest, among other animals. I was amazed to see all of these animals so close to the city. There is esentially a fence between the side of the park that borders the city and then a river provides another natural border, but the other two sides are completely open for the animals to come and go. The cost of the tour was expensive, however, if you don't have time to go to one of the other preserves like the Masai Mara, it is definitely worth the time and money.