The surprising level of the technical and scientific knowledge of the Hellenistic scientists is presented through several examples. The presented inventions and their applications belong to almost any aspect of science and technique. By examining these ancient inventions, it seems that they, almost partially, were imported by Eastern Cultures from those scientists who were in the entourage of Alexander the Great during his military campaigns in East. In the paper is also shown how this knowledge deeply influenced scientists of the Islamic Golden Age and of the Renaissance, giving considerable effects on the daily life of the European peoples. Finally, it could be observed that this knowledge reached the technicians up to the beginning of the XVIII Century and even the engineers of today can surprise themselves for those inventions and should recognize with gratitude the work of their ancient colleagues. Keywords: Hellenistic knowledge, Inventions of Classic Age, Ancient mechanics, Arabic technical knowledge, Renaissance engineers.