Robin's Nest

My neighbor found this nest when they pruned their tree.
The basic skeleton and support structure is made of twigs. It is thickly lined inside with horse hair.
We have stables at the periphery of our neighborhood. The neighbor who found the nest owns horses too. That is the reason she could tell that the brown and black strands were horse hair.
i wonder how many trips did the bird make back and forth to the horse stable to build this nest?
Must be a very intelligent bird.