Interestingly, cranes have been used to lift and move heavy items since antiquity. Fossilized fragments 7mm rope have been found in one of the caves at Lascaux and are estimated to date back to approximately 15,000 BC. The Ancient Greeks used cranes, as well, using men or donkeys to power them. According to the Bureau of Labor Statistics, there are approximately 40,000 crane operators employed in the United States today.