What is (was) this?

Well its obviously a bridge of some sort in Bellas Vistas, Madrid and I came across it on a walk today. It nagged me that I felt sure I had seen it before and that I knew what it was but had forgotten how, why or when!
Well later today I remembered. I had seen it before but from up a tower block where I gave a few classes some years ago. From the student's window it was quite clearly used at one time for carrying a track of some kind but now all there was to see was grass growing there. I asked my student who explained it was part of Madrid's long defunct tramway system!
I was pleased that my annoying mental itch earlier in the day had been gently scratched away!
Having said all that, I have just seen from Google Maps that its called Aquaducto de Amaniel!
So I am again none the wiser!

A former guest member wrote; Thank you for showing this interesting bridge. I tried to find some information, and on
structurae.net/de/bauwerke/amaniel-aquaedukt
they say that it is an active aqueduct. The site has been updated a last time actually in 2018 and they show two photos.
As I do not know so much spanish, I was not able to collect much information, but for example
www.exclusivasimanara.com/blog/galeria/374-el-acueducto-de-amaniel-en-1857
seems to say something similar.
I was not able to find information in connection with a tramway, but at
www.iagua.es/noticias/ayuntamiento-madrid/ayuntamiento-madrid-recupera-tramo-historico-viaje-agua-amaniel
the spanish word "tramo" is being used which might have been misunderstood. I would suppose, in this text, "tramo" stands for construction section (Bauabschnitt, in german)
At
commons.wikimedia.org/wiki/Category:Acueducto_de_Amaniel
they show several photos of it, but I do not find a verbal explication at wikipedia sites.
Best wishes and have a great day