Concrete? In Stonehenge? It's more likely than you think. Me, I think the article is over-stating how "unoriginal" the present Stonehenge is. At no point does it seem that they put new stones in, or altered the existing ones in major ways. I'd wager the later restorations were based on archeological information, but the article doesn't mention that. The tough truth is that ANY man-made object will need some touching up every few thousand years or so.