On the way back from a day trip to Mount Fuji, the expressway sign says another 15 km to Tokyo. We did some research on the internet to know how these distances are measured and what is the base location for these signs. We found out that the location of Kilometer Zero for JAPAN was Nihonbashi the bridge in central Tokyo!!!
There was a time when Nihonbashi was a wooden bridge with a great view of Mount Fuji! No more, but the location is still used as a base point to measure all distances on expressways.

To reach the Kilometer Zero point in Tokyo, visit the Nihonbashi bridge, easily accessible from the Tozai Line Nihonbashi Station and the Mitsukoshi-mae Station on the Ginza Line.
The old bridge below is overshadowed with the expressway which runs on top of it, but the stone bridge built in early 20th century still stands and is usable for regular traffic.
In the middle of the bridge you can see a metal plate fixed on the road which is the point from where all measurements are made. Watch out for the running traffic before you decide to go check the metal plate in the middle of the road!!!
We do not suggest you get between the traffic and see this sign in the middle of the road, but we took one quick walk when the signal was red and took a snap which is below.
You can check the same plate (an old version) on the side of the bridge, which is a safer option kept there as a memorial for you to take snaps of
The old metal plate is fixated on the road side facing the Mitsukoshi Department Store which is a good place to stop by and shop too.
Just FYI, the Kilometer Zero point is for roadways, while the Tokyo Station is considered the originating point of the national railway network and has several posts and monuments indicating 0 km of lines originating from the station. more on this soon…
The Olympics in 2020 may see a reconstruction of the overshadowing expressway to the underground the details of which are at Nihonbashi : Once upon a time…