Thank you very much to Dr. Ken Citron for contributing this article. If anyone has articles or photos of interest to other visitors to Porto Heli, I would welcome them. Anecdotes, exceptionally good (or bad) places or people, sites of interest, advice to pass on - anything and everything is grist for the mill.
The city walls had five gates and enclosed an area of 45 acres. Within the walls were about 500 homes with a population of about 2,500 people. In the fertile surrounding area olives, grapes and cereals were grown and sheep and goats grazed. The ruins can be seen on 4 levels.
Underwater - the sea has risen 2m since ancient times but on calm days the ruins can easily be seen under the water and comprise of a harbor, houses and streets. Also present are a Temple dedicated to Apollo, a Stadium where athletic competitions were held and some Baths of a type built later by the Romans.
The Lower City - there was a Mint producing coins showing the head of Apollo. The streets were on a regular grid pattern, each of the houses having a courtyard and well and some of the olive presses can be seen.
The Industrial site- halfway up the hill is a site with workshops thought to have been used for producing dyes.
The Acropolis - situated on the hilltop, it has a fine strategic position with views over the harbor and across the Argolic Gulf. There was a look-out tower, barracks and an altar for religious worship.
5,000 years ago the site of the Acropolis was occupied by ancient tribes. 2,500 years ago Halieis was a prosperous city, exporting agricultural products to Athens and elsewhere. During the wars between Greece and Persia it helped provide ships and, because of its strategic position, it was important in helping Athens in its fight against Sparta during the 27 years of the Peloponnesian War. The city appears to have been abandoned about 300 B.C. It was resettled between 400 and 600 A.D. by Romans and Byzantines. The site was thereafter abandoned and remained untouched for over 1,000 years. It was discovered and put on a map by the British naval chart ship HMS Beacon in 1838. Archaeological excavations of the site were made in the 1970's.
More information about ancient Halieis (a.k.a. Allieis, Alieis, Porto Cheli and so on) can be gleaned from the Greek Ministry of Culture website along with information and photos of many sites of interest in Greece.
The former assistant director and architect of the Halieis excavations has an excellent website with lots of photos & info so please visit his site.

Underwater ruins of Ancient Halieis.

The ruins of Ancient Halieis, along the South side of the Porto Heli bay.

Modern day Porto Heli.