Hmmm...any serious work done on this thing, yet? As in, a university-grade excavation or survey? It looks kind of big; however, if there is any "stone construction" here, it's entirely possible that the neolithic (or whichever-age) peoples could've dug into the hill and excavated some "chambers" inside it (a la Malta's Hypogeum), rather than actually building that entire hill piece by piece. At least, it's a more practical scenario. But of course only a properly-trained archaeology team would be able to make any useful determination.

But oh wait, properly-trained archaeologists are evil, supressive, and not to be trusted. Some one fetch Erich!