Pillar stones, sometimes called standing stones, are among the most common yet least understood prehistoric monuments in Ireland. They were erected across a vast span of time, from the Neolithic through to the early medieval period, and their purposes remain genuinely uncertain: territorial markers, burial memorials, astronomical indicators, or ritual focal points, depending on the site and the era. What is consistent is their presence, solitary and deliberate, in townlands that have been farmed and walked and lived in for thousands of years.