When you want to go to a zoo in the Tokyo area, your best option is Ueno Zoo. Located in Ueno Park quite close to the station, it is the oldest zoo in Japan. It is definitely a must visit if your passion is animals, or if you at least like to look at them.
Once you enter through the main gate after purchasing your tickets from the vending machine, immediately to the right is the zoo's main attraction, the Panda enclosure. If you think that placing the most popular animal right beside the entrance is a bit unusual as it may provide a letdown for the rest of the zoo, it actually allows the visitor to see them twice, once when entering and once when leaving. Of course this area is always filled with throngs of zoo goers, so pick your time to see them to get a clear view through the slightly dirty glass around the enclosure.
This part of the zoo is actually the upper-- or East Garden--part of the zoo that also houses a group of elephants that even put on a show at various times during the day (usually around their feeding time). Also in this part of the zoo are many species of birds (Owls, Eagles, etc.) in cages that mimic their natural habitat, albeit in a scaled down form. Past the birds you find the entertaining Gorilla Woods that house a number of Gorillas including recent baby Gorillas. As you keep going along the path towards the first of the rest areas, you also pass by the Tiger and Lion habitats. On the day I visited, none of these animals were particularly active, so viewing them was a bit difficult as they like to lay down in areas that were in the shade and hard to see from some angles. Continuing past the rest area with its numerous tables, you can see more Japanese birds and the Bat House. This rest area has a couple of short-order restaurants serving typical Japanese fast food. After this is one of my favourite areas, the Polar Bear area. I just happened to pass by right at feeding time and the staff made it like a show and got the Polar Bear to really work for its food. Beside this is a tank for Seals and Sea Lions, however with the exception of a couple of them, they mostly just laid on the rocks sleeping. On the other side of the Polar Bear habitat was Bear Hill that had a collection of different Bears in different sections. The next area is another rest area that has more upscale food and a restroom that you are able to change your baby in. Also in this area is the Monkey Mountain containing a large group of Japanese Macaques. Also here is the Monorail.
The Monorail will take passengers down to the other part of the zoo, or the West Garden. You are free to walk there via Aesop's Bridge, but taking a monorail for 1 minute is much more fun.
Down in this part of the park, you are immediately confronted with the penguins. To the left is a large pond that is also home to a few animals including water fowl and Lemurs. At the end of the pond is the reptile house that is so humid it is hard to stay long. However, the Galapagos Tortoise is well worth the walk. There is another entrance here as well. Continuing past this area are the real stars of the zoo, the large mammals. First there is the Okapi, followed by the Giraffes, the Rhinos, and the Hippos. The Hippos were a bit difficult as they continuously swam in the water which was quite dirty, so it was hard to get a good view of them, let alone a picture. Here is also another rest area with tables and another short-order restaurant.
There are also a few souvenir stores that were mostly selling Panda-related items but these seemed to be populated mostly by young children. One interesting item that is worth looking into is the Ubiquitous Communicator that is available for free for guests to carry around the zoo and get more information about any of the animals just by tapping the Communicator on a sensor located near the animal areas.
It is easy to spend a long time here so pack a lunch. It is definitely worth the time to visit and you will probably want to return. I know I do.