The greatest human inventions:

1. Wheel

2. Printing press

3. Penicillin

4. Compass

5. Light bulb

6. Telephone

7. Internal combustion engine

8. Contraceptives

9. Internet

10. Nails

11. Use of fire

12. Concrete

13. Magnifying glass

14. Batteries

15. Marine chronometer

16. Airplane

17. Refrigerator

18. Nuclear energy

19. Vaccines

20. X-rays

21. ₿