Tokyo has many highways (syutoko). However, most highways in Tokyo are built before Tokyo Olympic (1964 : Tokyo Olympic).
Tokyo was nothing just after 2nd war. maybe, you can check many photos in the Internet about Tokyo just after 2nd war.
so, the largest question is why there long distances of highways in Tokyo were built only less than 20years? Because if they were built from nothing, then it was needed more than hundreds years.
the answer is there highways were reused of moat around castle. Tokyo had been capital since 3-400 years ago(Edo period: 1603 – 1868). so, there moats were grown using for 300-400 years.
As following photos are a part of highway. You can see a wall on right side on each photo. They are a trace of moat. If you have interest in this seen, you can see Shintomicyo. I pined on a map on this blog.