AFAIK Yamanote Line is not the oldest line. Maybe oldest still in service?

There's a train statue at Shimbashi station that I believe commemorates the first line in Japan to/from Yokohama

https://en.m.wikipedia.org/wiki/File:JNR_C11_292_Shinbashi_S...

The original station is here https://www.ejrcf.or.jp/shinbashi/index.html just a few blocks from Shimbashi station. They built a new building there thoug the original platform is part of the building and a few sections of original track are encased in glass