A geological wonder, Giant’s Causeway is about an hour’s drive northeast of Derry on the coast in County Antrim. It is made up of around 40,000 black basalt columns in polygonal shapes, a unique landscape that has been named a UNESCO World Heritage Site. At the time the causeway was "discovered" in 1693, there was debate over whether it was man-made or the work of a giant known as Finn McCool, who was building a bridge to Scotland. (Geologists now believe the causeway was created by volcanic activity some 50 to 60 million years ago.) There are paths around the site, though you should take care: The footing is uneven, and good walking shoes are essential.