The archaeological site at Kefalovryso Portes is one of the most important prehistoric sites of western Greece due to the discovery of grand and unique remains of the Mycenaean era (17th -11th cent. B. C). The cemetery, which consists of tumuli with built chamber tombs and cist graves within them, two tholos tombs and several rock-cut chamber tombs, has been investigated to its greater extend.

To the northwest of the cemetery (plan 1), one can see the foundations of houses belonging to the nearby settlement, which lies close to natural spring providing ample water, named Kefalovryso (plan 1). The spring as well as the strategic passage at this point, from mountainous Elis to the fertile plain of Dymaia region and the Gulf of Patras, played the most important role for the choice of the site and the organization f the Mycenaean settlement.

The correlation of ancient testimonies (Pausanias, Strabo, Homer, Diodorus) to recent investigations could lead to the identification of the site at Kefalovryso Portes with Eleian Pylos. Apart from the important mycenean remains that came to light after the recent excavations, the geomorphology of the region, the deep caves with their short entrances as well as the modern place-name Portes (meaning door), match to the references of Pausanias for the Gates of Ades and the worship of the dead in Eleian Pylos.

The prehistoric settlement (plan 1) has not been investigated yet, so apart from its location, more information cannot be provided at present.

The cemetery lies on the east of the settlement, occupying the summit plateau and the slopes of a low hill made up of soft sedimentary rock (plan 2). Although it had been repeatedly looted in the past, the archaeological excavations that begun in 1994, have brought to light a particularly rich necropolis, where one can encounter all the elements of the evolution of Mycenaean burial architecture. Almost all types of graves used from the early years of the Bronze Age until its end, are present at Portes.

To the early phase of the cemetery belong at least two family tumuli. The stone-built circular perivolos (enclosure), which surrounded tumulus A and contained the earth on its inside, has been preserved in situ. Only fragmentary remains have been preserved from tumulus C. Both tumuli date to ca. 1700 B.C

Inside the tumuli the remains are preserved of built chamber tombs, founded on a rectangular carving, cut on the soft rock. This type of grave is an underground rectangular structure with built entrance on one of its narrow sides. Large slabs covered their surface. Built chamber tombs are a very rare type and they were in use from the 17th century B.C until the beginning of the 15th century B.C. Graves of the same type, but with no relation to a tumulus, have been investigated on the hillocks behind the buildings (plan 2). These graves had been seriously damaged and looted already in ancient times, but the remains of the burial layers provide us valuable information for their dating.

During the 14th and 13th centuries B.C, simple and small cist graves were added to tumulus A. They were built with upright slabs and they reflect the sporadic use of tumuli during that period, which gradually led to the abandonment of this particular burial custom. Isolated groups of cist graves, constructed of built sides as well as upright slabs, were also found in the cemetery area and they date to 14th and 13th centuries B.C too. The use of this type of graves was not very popular in mycenean times and should be explained as an impact of earlier burial customs, related with tumuli.

The extremely rare type of tholos tomb is also represented in the cemetery at Portes. Two tombs of this type have been located, but have not been investigated yet. It seems that they had collapsed and fallen out of use already by the middle of the 14th century B.C and they were destined for the burial of the eminent families of the settlement, those who ruled and had the power. The tholos tombs of Portes belong to the early examples of the type in mainland Greece, since for their most part they were constructed above ground. Their use was almost contemporary with that of the tumuli, which were the first burial structures/monuments that were established on the hill.

The most common grave type in use is the chamber tomb, of which 30 have been investigated at Portes up to now. Chamber tombs made their appearance slightly before the abandonment of the earlier tumuli graves, at about the beginning of the 15th century B.C and were being used without interruption for five centuries, until the decadence of the Mycenaeans in the end of 11th century B.C. They are subterranean tombs, cut in the bedrock in the form of a chamber, usually circular in plan. Access to the chamber is provided through a long, downwardly sloping dromos (passageway), which leads to the stomion (entrance door). The bedrock had been exhaustingly exploited due to limited space and the need for many tombs at the same time. The dead were placed at the floor of the chamber and sometimes in pits that were cut in the floor. Numerous grave goods, useful to the journey to the Underworld, accompanied the burials.

The unique character and great significance of the Portes cemetery may be attributed to a number of reasons; the built chamber tomb of tumulus C, (C1) has monumental dimensions and is the largest so far known in mainland Greece. Apparently it would have belonged to one of the most powerful families of the settlement between the 17th and 16th centuries B.C. The burial of a warrior from the end of the 12th century B.C, which was found intact on the floor of chamber tomb 3, probably is the most important Mycenaean burial of those times in Greece. Among the offerings which accompanied the deceased several clay pots should be mentioned as well as a bronze bowl, a knife, a spearhead, a sword, a pair of bronze greaves and a bronze-plated helmet, unique in that it preserved traces of its straw lining. However, leaving aside the wealth of its goods, this burial provides valuable information concerning the social, administrative and military organisation of the Mycenaean world during the 12th century B.C.