Nihonbashi bridge is a very historic site in Tokyo. Nihonbashi actually translates to Japan Bridge.  It is in the Chuo district of Tokyo and has linked the areas on either side of the river at this site since the 17th century.  It was initially a wooden bridge and was first constructed in 1603.
From reading about it, it appears that this is the official point of origin for Japan’s five main streets, especially relevant during the Edo period.  It still bears a bronze signpost with the words “Origin of Roads in Japan,” and it serves as the reference point for all roads in the country. ie the distances to Tokyo are to this point.

During the 17th century the Nihonbashi bridge was known as the Edo bridge and was the eastern terminus of the Nakasendō and the Tōkaidō, roads which ran between Edo and Kyoto.
The wooden bridge was replaced by a larger stone bridge in the Meiji era and that is the same bridge that is there today.
What is different though is the huge expressway that has been built over the top of it.
That hasn’t helped the view at all!
The good news for the bridge, is that despite this its historical significance is recognised and there are even moves afoot to restore it…  Although moving an expressway is a pretty major task.  Anyway, its a wonderful historical piece of Japan and worth a visit.