It makes sense to fly it over a Civil War battlefield, but only if the US flag is flown there as well. (In fact, it’d be even better if the US flag of the time were flown there. It’s still legal to use any old US flag design.) It has a tie to the history of the battlefield.
To answer the question you are probably at least as interested in, I don’t think it makes sense to fly it at any state capitol building.
