This is a door I have shared before, very early on Notes, and in other places. And with good reason. It is a Door of Interest, one which begs many questions and provides few obvious answers, like all the best portals.
Some places, like here, in medieval Bourges in the heart of France, are positively overflowing with such portals. A city renowned for its Gothic cathedral, it was also a centre for alchemy, once upon a time; Gothic alchemy makes some sort of sense to me.