Dating to the 4th century BC or early Hellenistic period, the modest structure represents the oldest known Greek bridge with a voussoir arch.

There, an artificial channel of 2.15 m depth ran parallel to the ancient city walls, separated by an 11 m wide street running in between.

The sidewalls of the conduit were made of at least four layers of poros stone blocks, the same material also employed for the arch.

[2] Nearly at its midpoint, the canal is crossed by an 8 m broad arch of wedge-shaped stones which served as a footbridge.

Its surprisingly low rise, in the order of 1 to 3−4, gives it the appearance of a segmental or even multi-centered arch, of which it is the only known example in Greek architecture.