One of the circles of Stonhenge (I think the inner small one) uses a particular blue stone (Dolerite - some of which are thought to weigh up to 4 tonnes!) which can only be found in the Preseli mountains of West Wales, which means that they had to be transported well over 200 miles by sea, river and land. I seem to remember some historians trying to recreate the journey recently using the methods they thought available at the time, but the stone went overboard somewhere in the Bristol channel!