Are there other examples of similarly old roads or routes that are still in use today? I know of the Grand Trunk Road [1] and other examples would be cool to learn about.
There are hundreds of roads in what used to be Rome and the Spanish empire, but very few preserve their ancient pavements as eventually they replaced by modern roads or abandoned during longer periods of times. Three examples:
Vía Augusta, from southern Spain up to Rome.
Via claudia Augusta, from Germany to Rome.
El camino Real, in America (Mexico and USA, also 2500km approx)
Sections of the Mullan Road still exist in the US West. It is/was one of the first wagon roads to cross the Rockies. Somewhat old for the New World, anyway.
https://en.wikipedia.org/wiki/Mullan_Road
1. https://en.m.wikipedia.org/wiki/Grand_Trunk_Road