«Polygonal walls and the astronomical alignments of the Acropolis of Alatri, Italy: a preliminary investigation. Giulio Magli Dipartimento di ...»
Polygonal walls and the astronomical alignments of the
Acropolis of Alatri, Italy: a preliminary investigation.
Dipartimento di Matematica del Politecnico di Milano
P.le Leonardo da Vinci 32, 20133 Milano, Italy.
1 Introduction: polygonal walls in Italy
The so-called cyclopean or polygonal walls are huge walls of megalithic blocks cut in polygonal
shapes and fitted together without the use of mortar. Many walls of this kind were constructed
during the Bronze Age in the Mediterranean area (probably the most famous are the walls of Mycenae).1 Slightly less known, but equally impressive and magnificent, are the walls visible in many Italian towns, spread into a wide area which spans from Umbria to Campania. Besides Alatri, which will be the subject of the present paper, those of Segni, Ferentino, Norba, Arpino and Circei are worth mentioning.
Polygonal walls are traditionally classified into three types or manners. The first type is constructed with blocks of medium dimensions with coarse and inaccurate joints, the second type shows a good stonework with few wedge fillings between main blocks, and finally the third manner is simply perfect, with joints so accurately prepared that it is impossible to insert even a sheet of paper or the blade of a pocket knife between two adjacent stones. The small town of Alatri, in the Frosinone provincial district at one hour driving from the center of Rome, is the place where this “third manner” of polygonal walls is still visible nearly intact, as it was constructed at least 2400 years ago.
The builders of the polygonal walls in Italy have not been identified with certainty.
A long standing debate opposes those who think that most of the walls were built by the Romans or by Latin people but under the strict and direct influence of the Romans, and therefore date the most ancient of these huge constructions not before the fourth century BC, and those who think that Romans simply had nothing to do with such buildings and therefore that the walls can be several hundreds of years older than this.
The debate on the builders of the Italian polygonal walls was active in the beginning of the 20 century, when most scholars adhered to a long-standing tradition which attributed the construction of the walls to a people called Pelasgi, who allegedly come to Italy during the end of the Bronze Age (1200-800 BC) importing the Hittite-Mycenaean technology. However, proofs of the existence of this people are lacking and, as a matter of fact, the diffusion of techniques need not to be identified with the diffusion of a population bringing it, since a technique can be imported via cultural and economic contacts or can be independently invented (it suffices to think to the magnificent polygonal walls built by the Incas two thousands years later). Thus, the walls might be attributed as well to the populations inhabiting the areas before the Roman expansion, people who were, like their contemporary Etruscans who lived in adjacent areas, in active economic and cultural contacts with the civilizations of the Mediterranean sea. In 1957 however, this explanation was refused by the authoritative scholar Giuseppe Lugli2 who re-formulated, this time as an apparently unassailable dogma, the aforementioned idea that the polygonal walls were nothing but one of the types of roman walls, a type called by him – I repeat, by him - opus siliceum, to be added to the already well known types of roman walls, such as for instance opus quadratum, walls of stone blocks cut as parallelepipeds and set in place on horizontal layers without mortar, and opus caementicium, in which the core of the walls is made of pieces of stones mixed with mortar and sand, while the external faces are of small stones or bricks.
Recently, the position of many scholars on the builders of the polygonal walls is again becoming more dubitative3 and I deserve to deal at depth with the important problem of the dating of the walls in a separate publication. However, as we shall see, the dating of the Alatri walls is of fundamental importance for the present paper, since the results support a pre-Roman construction. Therefore, a discussion of the topic is necessary.
2 On the dating of Italian polygonal walls Dating of stone building per se is impossible. While it is common to find on Roman bricks or even on Roman square blocks the presence of marks and timbres identifying the “producers” of the material and in many cases also the year of its extraction from the cave, no traces of this kind have ever been found on polygonal blocks anywhere in Italy. Actually Lugli’s dogma of a Roman dating was founded only on a very debatable interpretation of a statement of the roman architect Vitruvius4, who cites the existence of a sort of construction called silice without actually describing it, and on a even more debatable interpretation of a short inscription (dated around 140 BC) which runs on the walls of the Ferentino acropolis. In this inscription, the censors (magistrates) who certainly built the upper part of the construction in square blocks, where the inscription is actually located, credit themselves also of the construction of the lower part of the same building, in polygonal blocks, calling it, again, silice. The text is, however, quite ambiguous.5
Against Lugli’s dogma many points can be raised, perhaps the main being the following:
1) Romans were, of course, skilled in working with huge objects, such as the granite columns of the Pantheon in Rome, weighting more than two hundreds tons and coming from south Egypt.
They were skilled in building with huge blocks as well, as one can easily check visiting, for instance, the internal rooms of St. Angelo Castle in Rome, which were originally built as the funerary chambers of the Mausoleum of the emperor Adriano. However, all the stone buildings in Rome were constructed with square blocks (opus quadratum) from the very beginning of the Roman civilization, as one can see, for instance, from the remains of the archaic defensive walls of the town, on the Palatino hill, dated around 530 BC, or from the internal walls of the prison called Carcer Tullianum, which were built between the 6 and the 5 century BC, not to mention the first complete defensive walls of Rome, called serviane, dated around 390 BC. The fact that polygonal walls were never built in Rome is sometimes explained with the observation that the quality of stone most easily available near the town, called Tufa, is not easily cut in polygonal blocks.6 If this argument can perhaps explain the most ancient constructions in Rome, it is, at least in my opinion, really flawed insofar as the civilization which was going to become the owner of the whole western world is concerned.
2) The megalithic style of the polygonal walls (with blocks that can be as heavy as 30 tons) requires techniques which are completely different from those of opus quadratum, in which even the hugest blocks reach at most the weight of a few tons. Romans made large use of tackles and pulleys, but stones like those visible in Alatri, in Segni and in many other places can be efficiently raised only with the help of earth ramps (perhaps one can raise one stone of this kind with the help of an appropriate system of pulleys, but building kilometres of walls with such devices looks impossible). In addition, before putting third-manner polygonal blocks in situ a hard work of fine-cutting is required, in order to fit perfectly the angles of the stones already positioned, while square blocks can be used exactly as they arrive from the cave. Once again, it is frankly difficult to believe (or at least, it is difficult to the present author) that such a spectacular and sophisticated technique was deserved to the province.
3) Techniques based on huge blocks were used by the Romans for the restraint walls of earthworks in sub-urban “Villas” (factories) of republican age (II-I century BC). However, such walls cannot be classified into one of the three manners and in fact in order to describe them Lugli was obliged to introduce an ad hoc a “fourth type” described as “very near to the square blocks technique”. In the walls constructed with this “fourth manner” - actually a sort of “missing ring” of Lugli’s dogma - there is a clear tendency to the use of horizontal setting layers, although the disposition is inaccurate and some blocks are trapezoidal and exhibit acute angles. This style is actually the unique used in most, if not in all, the foundations of “Villas” and, as a matter of fact, rather than considering it an “evolved" polygonal blocks technique it could be safely (and very reasonably) interpreted as a naïve way of building with square blocks, which was adopted because the construction did not require aesthetical beauty (for instance, the walls were used for agricultural terraces). The construction technique of the walls of the Acropolis in Ferentino could perhaps be included in this “fourth manner” as well, thereby accepting the credits of the two censors.
4) If the Romans used such complicated megalithic techniques, it is strange that they did not leave any document describing or at least depicting it, even in disguise. There is no Roman historian citing them, including Livius who described the foundation (“deduction”) of many colonies where, according to Lugli’s dogma, polygonal walls were constructed immediately thereafter the setting of the colonists. We do have many stelae illustrating buildings or even construction techniques of buildings, but in all such documents the blocks shown are regular, squared blocks.
5) Another point which, at least in my view, shows how much the “Roman dogma” is far from being the truth is the following. The megalithic builders did not use the arc: their “arcs” are trilithon doorways or the so called “false arcs” (a very bad terminology) composed by corbelled blocks forming a “V” upside down. The Roman architects instead used the arc from the very beginning of the Roman civilization. As a consequence, one can see Roman restoration and integration of polygonal walls in which previously existing “false arcs” were substituted by “true arcs”.
As we have seen, those people who refuse Lugli’s dogma (people to which I do belong) usually think that the construction of most of the walls pre-dates the Romans and can be attributed to the populations inhabiting the area between the VIII century BC and the Roman expansion in the IV century. Actually however only a few sites have been dated so far in a secure way (with the use of organic material or pottery associated to the walls) and some of them turned out to belong to such a period.7 Further archaeological work in this direction is certainly advisable and the old idea of a Bronze Age retro-dating of the walls cannot, at present, be ruled out completely. As a matter of fact, it already happened in the history of archaeology that the dating of a stone building had to be shifted back in time of as much as one thousand years (I am, of course, referring to the Sarsen phase of Stonehenge, today dated around 2100 BC 8).
3 The Alatri Acropolis
The city of Alatri was built around a small hill, and the town is surrounded by megalithic walls of which many remains are still visible today. The Acropolis in turn is a gigantic construction built on the hill and covering the top of it. In some sense the hill was adapted and sculpted in such a way as to obtain a sort of “geometric castle” dominating the center of the town (Fig. 1). The Acropolis is so impressive that the famous German historian Gregorovius (1821-1891) reported “an impression greater than that made by the Coliseum”.
The perimeter of the building is defined by huge walls which give to it a polygonal shape with six sides ABCDEF (Fig. 2). The polygonal shape of the Acropolis actually looks like a giant replica of one of the stone blocks of which the Acropolis itself is constructed. The access to the Acropolis was possible trough two doors, today called Porta Minore and Porta Maggiore. Porta Minore is a small trilithon doorway (Fig. 3), and on its lintel a symbol composed by three phalli disposed as to form the upper part of a crux can be discerned (Fig. 4). Porta Maggiore is one among the most magnificent megalithic structure of Europe, and it is composed by a tunnel of huge stone blocks with corbelled ceiling and a monumental trilithon access (Fig. 5). After the door on the C wall, a short bent wall leads to side D which contains three huge “niches”. These “niches” look as basements for statues (Fig. 6), however no kind of artistic find has been found here or elsewhere in the Acropolis. Thus, the unique “message” left today by the builders of this monument is the halfcrux shaped phallic symbol on the small door (a statue of a lion, badly damaged, lies on the ramp on the north side, but the dating of this sculpture is unknown).
On the top of the Acropolis a further megalithic structure, lying on a natural rocky platform, existed. Archaeologists call this structure ierone, thinking that it was the basement of a temple.
However, no proof of this statement has ever been found. The structure was constructed with enormous stone blocks perfectly cut and joined, without mortar, in such a way that it is impossible to insert even a paper sheet between two blocks (Fig. 7). On this building the Alatri cathedral was later constructed, so that today only the lower courses of stones remain visible, under the church.
4 Solar alignments and geometrical symmetries in the Alatriconstruction plan.
The first to propose the idea that the city of Alatri and its Acropolis were planned on the basis of geometrical and astronomical alignments was a local historian, Don Giuseppe Capone, in 1982. His work is poorly known and of very difficult access, therefore I will review here the most important discoveries of this scholar. 9 Capone studied the geometry of the city plan and discovered that there exist a sort of “privileged point” (indicated by O in the figures 2 and 8) which lies just behind the northern wall of the megalithic structure at the center of the Acropolis (and thus it lies today near the northern wall of the Church, se again Fig. 7). With respect to the point O, Capone individuated many geometrical
symmetries and astronomical alignments (Fig. 8):
1) The H corner at north-east of the acropolis defines a direction OA which individuates the rising sun at the summer solstice.