The Giant's Causeway is an area of about 40,000 interlocking basalt columns, the result of an ancient volcanic eruption.It is the most popular tourist attraction in Northern Ireland.Carrick-a-Rede Rope Bridge is a rope suspension bridge near, Ballintoy, County Antrim, Northern Ireland. Carrick-a-rede means 'rock in the road'. It is thought salmon fishermen have been erecting bridges to the island for over 350 years.