How?!

Stunning architecture inside "the" Alhambra. I can't remember the exact details of how it was constructed (it involved an intricate multi-layered scaffolding system), but I remember being pretty amazed at the time.

What amazed me even more was the incorporation of fluorescently labelled DNA into some of the mortar used for repair and restoration over the years. This novel type of mortar allows historians/restorationists (?) to distinguish between different mortar types (and thus infer what was repaired and when), as it fluoresces when exposed to infra-red light.