3. The Poulnabrone Dolmen, Ireland
Ireland’s vast, stark plains have dozens of ancient sites dating to the Neolithic period. Some of them resemble the Stonehenge in their basic design. Others are mere caves. In barren, rocky County Clare stands the Poulnabrone Dolmen, a solitary, large, irregular-shaped stone construction that marks a burial chamber. The thought that this simple structure has stood at this location for thousands of years can be a moving one.