Ruin is not a negative thing. First, it is obviously not a thing. One could write [. . .] a short treatise on the love of ruins. What else is there to love, anyway? One cannot love a monument, a work of architecture, an institution as such except in an experience itself precarious in its fragility: it has not always been there, it will not always be there, it is finite. And for this very reason one loves it as mortal, through its birth and its death, through one's own birth and death, through the ghost or the silhouette of its ruin, one's own ruin--which it already is, therefore, or already prefigures. How can one love otherwise than in this finitude? ("Force of Law," Acts of Religion [London: Routledge, 2002], 278)
Mike Johnduff quotes the same passage and has some interesting things to say about Derrida, ruins, and love (mainly riffing off Memoirs of the Blind) at Working Notes. The image above comes from Zingology. And there are some further thoughts about ruins at borrowed city, not least "Love Among the Ruin Porn" parts one (Highland Park) and two (the Heidelberg project).