A mirador is a view point with a panoramic view.
Mirar in Spanish means "to look".
So a mirador is a "looker" or a place where you look from.
The Mirador de San Nicolas has a wonderful panorama of the Alhambra.
It is in the Albaicin and is across a valley from the Alhambra.
It is free, it is just a public square.
To see some photos and more information use this page.
https://granadainfo.com/dogranada/mirador_san_nicolas.htm