I don't know the story behind this. A Jihad Watch reader spotted the "Allahu akbar" painted on the side of a burned house and sent me the photo. Perhaps the one who painted it was responsible for the burning. Or perhaps he just wanted to make a Qur'anic point that other Muslims have made at the sites of other non-Muslim ruins: "Say, 'Travel through the land and observe what was the end of those before. Most of them were idolaters'" (Qur'an 30:42). That is, submit to Allah or you'll end up ruined as well.
After a short time the inscription was painted over.
Photo thanks to C.