The Citadelle at Besancon is one my all time favorite things and places.
I am unsure why, aside from that geeky middle school girl side of me that favors historic locales with good stories. The Citadelle's stony, austere, gorgeous. I like to sit beside it and read and draw and think about all the soldiers who guarded it, why it was important strategically, and German armies trying to storm up the Jura to wage assaults on it. It's a fun place to sit, and I think it inspires a kind comfortable awe, if that is something you can say about "awe." Like, it's big and imposing, but not so big and imposing that you don't feel ok drinking wine near it.
That's my kind of awe-inspiring.