Link to photo dump.
A couple of years ago, I saw a photograph of Giants Causeway in a National Geographic magazine, and I stared and stared at it. I just couldn't believe that what I was seeing was a natural phenomenon. It looked so obviously carved by humans. I thought, "That's a place I need to see some day."
When my dad picked this particular tour, I didn't realize that Giants Causeway was on the itinerary. In fact, I didn't realize it until a few days before we left. So basically by pure coincidence, I got two items crossed off of my bucket list this trip (Stonehenge being the more obvious one).
That last image is a digital panorama I stitched together on my computer, rather than in the camera. I didn't do a great job of giving the software well-matched images to work with. But it's good enough for you to see that the formations of hexagonal basalt columns extends well beyond the highest concentration, which is in the couple of acres that we were exploring. You can see one large cluster in the middle of the cliff face. And one of the most picturesque clusters--much too far away for us to get to in the limited time that we had--can be seen protruding up from the left edge of the cliffs, about 2/3 of the way from the water to the top, though you may need to open the full size of the photo to see it. It's called the Chimney Stacks, and it's like a small version of Devil's Tower in Wyoming. (Devil's Tower, by the way, is the same type of geological formation: hexagonal basalt columns. See the close-up photo in the Wikipedia entry here).
If you hadn't had enough yet, look at some of the lovely photos of the area that National Geographic readers have submitted, here.