Hibiya park in Tokyo covers an area of 161,636.66m2 between the east gardens of the Imperial Palace to the north, and the Shimbashi district to the south-east. Its easy to get there by foot from Yurakucho station. This park has three ponds and quite a few trees. Autumn is especially lovely in this park, and should not be missed if you happen to be in Tokyo this time of the year.
Find out more about Hibiya Park.