Leonardo da Vinci may well have been the greatest inventor in history, but he had very little effect on the technology of his time.

Da Vinci drew sketches and diagrams of his inventions, which he preserved in his notebooks, but if he lost interest in building them or was never able to convince one of his rich patrons to finance construction of his designs, we do not know. As a result, almost none of da Vinci's inventions were built during his lifetime. And because he never published his diagrams, nobody else knew about them until his notebooks were discovered long after his death.

That's a pity, because da Vinci's designs were spectacularly ahead of his time. If they had been built, they might have revolutionized the history of technology, though many of them may have been impossible to build with the tools available in the 15th and 16th centuries. In recent years, however, engineers have begun to construct models of da Vinci's amazing machines and most of them actually work. 

Adapted from 

http://science.howstuffworks.com/innovation/famous-inventors/10-leonardo-da-vinci-inventions.htm