Historical and archaeological evidence shows that ancient Hellenes had developed underground aqueducts since the prehistoric times. However, innovative methods of underground aqueducts were developed in Hellas mainly during the Archaic, Classical, Hellenistic, and Roman periods. Since the well-known tunnel at the island of Samos, Hellas, was designed and begun its construction (ca. 550 bc) by Eupalinos of Megara (the first civil engineer in history), several underground tunnels (with and without well-like vertical shafts) were implemented in the country. The goal of Eupalinos tunnel was to transfer water into the town from a spring. This tunnel, representing the peak of ancient hydraulic technology, was dug through limestone by two separate teams advancing in a straight line from both sides of the mountain. Delivering fresh water to growing populations has been an ongoing problem since ancient times. Several underground aqueduct paradigms (e.g. Peisistration in Athens, Polyrrhenia in Crete), some of which are in use even today, are presented and discussed. After late Roman times and the Adrianic aqueduct a gap of about 1,700 years in construction of such hydraulic works is noted. However, a remarkable development of tunneling in Hellas appeared during the last 50 years due to the ‘cosmogony’ of the construction of infrastructure projects using modern technology, e.g. Evinos-Mornos aqueduct with 15 tunnels of 71 km total length and the diversion tunnels in Sykia to the Thessaly plain and Messochora of the Acheloos River of 17.5 and 7.5 km length, respectively. Also, very recently three small conventional tunnels and one tunnel boring machine (TBM) were constructed in Aposelemis aqueducts used for water supply of Iraklion and Agios Nikolaos cities in Crete. As a consequence, significant design and construction experiences were gained. Overall, it seems that underground aqueducts of modern societies are not very different in principle from those during antiquity.