The Giant's Causeway is an area of about 40,000 interlocking basalt columns, the result of an ancient volcanic eruption. It is located in County Antrim on the northeast coast of Northern Ireland, about 4.8 km northeast of the town of Bushmills. More details are in: http://en.wikipedia.org/wiki/Giant's_Causeway
Many thanks to Vivienne for sharing the following 2 photos.
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