Edo Open Air Architectural Museum
江戸東京たてもの園 is not a must-see but a very pleasant way to spend a few hours outside. It's free to get in on January 2nd and 3rd (check their website- other wise just 400 yen) and it's a good way to spend a couple of hours walking around looking at 30 or so old buildings. To look inside the houses, you'll need to remove your shoes so better have footwear that's easy to take off. There are a few places to get food inside as well. In the spring, there are many plum and cherry blossom trees. There's a big park right next to it-lots of families there on weekends. If you like this type of open-air museums, check out Nihon Minkaen Folk House Museum 日本民家園 in Kawasaki too.