Tunnel of Eupalinos

Location Description

37°41'40.70"N, 26°55'48.37"E

Project Location

37.75516396637261LOL26.996416174806654

Historical Context

Polycrates was a tyrant who wanted to provide water for his city. “Delivering fresh water to growing populations has been an ongoing problem since ancient times. There was a copious spring at a hamlet, now known as Agiades, in a fertile valley northwest of the city, but access to this was blocked by Mount Castro. Water could have been brought around the mountain by an aqueduct, as the Romans were to do centuries later from a different source, but, aware of the dangers of a watercourse exposed to an enemy for even part of its length, Polycrates ordered a delivery system that was to be completely subterranean.” Polycrates hired a Greek engineer named Eupalinos to design the waterway. (Apostol, 2004)

Approximate Year of Completion

Sixth century B.C.E [Hughes, ?]

Duration of construction

“No one knows exactly how long it took to complete the project, but estimates range from 8 to 15 years.” (Apostol, 2004)

Project description

This water tunnel is 1,036 meters long. “It was dug through solid limestone by two separate teams advancing in a straight line from both ends, using only picks, hammers, and chisels. It averages two meters wide and two meters high (Apostol, 2004).  Fig. 1 shows an inside view of the tunnel.

Fig. 1: Inside the Tunnel of Eupalinos (Source: Torben Bolhøj)

Construction details/observations

A theoretical method proposed by Hero of Alexandria five centuries after the completion of the tunnel “calls for a series of right-angled traverses around the mountain beginning at one entrance of the proposed tunnel and ending at the other, maintaining a constant elevation [see Figure 3 and 4]. Fig. 2 shows the clay gutters used to guide the water around in the tunnel.

Fig. 2: "Clay gutters like these were found in the bottom of the tunnel’s water channel. They could have been joined at right angles by L-shaped pieces, and used as leveling gutters around the mountain.” (Apostol, 2004)

Fig. 3: "At the southern end, the water channel is a staggering nine meters lower than the floor of the tunnel." (Apostol, 2004)

 Fig. 4: "Hero of Alexandria's theoretical method for working out the line of a tunnel dug simultaneously from both ends." (Apostol, 2004)

Other significant comments

“Two other famous examples are the much shorter, and very sinuous, Tunnel of Hezekiah (also known as the Siloam tunnel), excavated below Jerusalem around 700 B.C., and a much longer tunnel under the English Channel completed in 1994.” (Apostol, 2004) 

Sources and references

Hughes, Dan.The tunnel of eupalinos.Retrieved December 4, 2014, from http://homepages.cwi.nl/~aeb/math/samos/

Apostol, Tom. (2004). Tunnel of samos.(1), Nov. 30.

Project Id

DJP-04-14