This geological monument symbolizes the Island of San Pietro. The name (”the columns”) refers to its morphological aspect. It consists of a couple of isolated stacks of welded pyroclastic volcanic rocks (rhyolitic ignimbrites) dating back to the Middle Miocene (Langhian), that is about 15 million years ago. The stacks were formed and isolated over a thousands of years as a result of the intensive erosive activity of the sea on the cost. The pillars, originally 16 meters high below sea level, in the last two years were subjected to the wrecking action of the storm surges that generally characterized the southern coast of the Island. As a consequence of that, the shorter and the nearest stack to the coast, today is halved because of the several collapses suffered by the structure. This fact caused dismay both among locals and all those people who love the monument, considered as a shared good which has been included in many touristic itineraries.