http://www.mckeonstone.ie/ At Mc KeonStone's quarry in Threecastles ,Kilkenny , 1000 tons of Irish Blue Limestone and 3 caterpillar excavators battle it out ! This wall of stone had not moved in 250 million years and had been diamond sawn into one large chunk of 11metres high , 2.7 m deep and 13metres long ( 386 cubic metres ) . The power of three caterpillar excavators was need to topple this monolith. Quarry manager Peter Dowling orchestrated the movement of the three machines until gravity takes over . This quarry has been owned and operated by Mc Keon Stone Ltd since 1960 , and is the source of Europe's Best Blue Limestone.