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Everyone loves Nihonbashi!
Have you ever been aware that Chuo-dori is bent in the word "ku" here?
Why didn't you keep it straight even though it was a flat road? I have a question.
Let's take a look at the map.
Geographical Survey Institute Digital elevation Topographic Map "Kanto" - "Tokyo Metropolitan Area"
Since it is divided into color according to altitude, you can clearly see high and low places.
Looking north of Chuo-dori, the area near Ochanomizu Station is as high as a plateau. It was just said to be "Surugadai" or "Kadoyama". From there, a small green highland stretches toward the south. In the so-called "Edo Maejima", Chuo-dori passes through the middle of it.
By the way, the area between the slightly highlands where Chuo-dori is located and the Imperial Palace (Edo Castle) has a lower light blue color. It's the old "Hibiya Inlet".
In other words, "Edo Maejima", which extends south from Ochanomizu, turns around Nihonbashi and extends further south, and Chuo-dori passes through the middle of it. You can see that it is bent in the shape of "ku".
By the way, Nikko Kaido (Nikko Dochu) goes from Nihonbashi to Asakusa, but if you look at the same digital altitude topographic map, it extends slightly green. After all, the road in the Edo period probably means that the route was decided by choosing a low altitude.