"Curiosity, scholarly, spiritual, fun or a deep sense of yearning to connect with the spirit of an ancient place?"
Boringly, I've got to say All of the Above.
Plus Nature plus Landscape plus Aesthetics.
(Since taking up amateur painting I feel like I've grown extra eyes and aesthetics has become a dominating delight. It's everywhere at ancient sites and I missed it all before. Everyone should do it, for that reason alone).