Took a slight detour from our planned trip last summer to spend a couple hours at Chartres... Amazing Cathedral.
Haven't spent much time on this sort of thing... played with some filters, something like Vintage Grunge II in Topaz Adjust and Crystalize in PS, I think a yellow fill layer, too. Gray stone against a grey sky started it off.
grey against grey is hard to work with. Your treatment does give it an "old" look, good for the theme. Still, the lights seem a bit blown to me. I adjusted highlights and shadows a bit. May or may not suit your vision.
Thanks much for the comments. Hazel, I like your repost. I was thinking along the lines (for the OP) of a washed out, faded print where the ink was seriously degraded ;-)... I took another look at the original and discovered its, uh, charm. One of those doh moments... just went back outside so exposure at ISO6400 was shutter limited at 1/8000 (f/2.8 at 70mm) for a completely blown sky. Regular processing (for me) comes to this (a different click on the string from OP):
Wow, this one reminds me of a school assignment from way back when, which was to shoot something against a backlit sky while maintaining detail (or recovering later on in the print process). The original does have a bleached out appearance and to that end, it's successful. Though my eyes do prefer something a little less harsh. Interesting approach!