Carrickfergus Castle is located in the county of Antrim in Carrickfergus, Ireland. The Norman castle was built on the shore of Belfast Lough in 1177 by John de Courcy, but he was ousted by Hugh de Lacy in 1204. The castle has a long history of sieges and changing hands. The structure began with a 40-meter keep with four-meter-thick walls. The last building created was the stone gatehouse that had a portcullis and a drawbridge over a moat. In 1797, the castle was used to house prisoners of war and was heavily defended during the Napoleonic wars. It was used by the army until 1928 and served as a garrison and ordnance store during WWI and an air-raid shelter from 1939-1945 during WWII. Ownership was transferred to the government for preservation in 1928. The four-story castle has a second-story stair entrance. The ground floor has no windows and houses the castle’s water supply. The lord of the castle held court on the second floor, while the top floor housed his private accommodations.
Clochán an Aifir (Giant's Causeway,) County Antrim, Northern Ireland, 2005
This outcropping of basalt columns is a result of an underwater eruption. The hot, liquid basalt crystalized when it hit the water, resulting in the hexagonal columns.
Legend has it that it was built by the giant Fionn mac Cumhaill (Finn MacCool) so that he and the Scottish giant Benandonner might meet in the middle of the sea to fight. There's a matching set of basalt columns on the Scottish shore opposite it, which lent some credibility to the legends. [They're really there because they're part of the same eruption.]
I mostly think it's there because Mother Nature likes to throw in little flourishes every now and then. (All you need to do is just look around you for further examples.)