Mediterranean Archaeology and Archaeometry, Vol. 16, No 4,(2016), pp. 291-295
Copyright © 2016 MAA
Open Access. Printed in Greece. All rights reserved.

10.5281/zenodo.220949

LA GESSERA: AN IBERIAN BUILDING FOR WORSHIP?
(TARRAGONA, SPAIN)
Manuel Pérez Gutiérrez1, David Bea Castaño2, Jordi Diloli Fons2, Jordi Vila Llorach2,
Marc Prades Painous2
Higher Polytechnic School of Ávila, University of Salamanca
C/ Hornos caleros, 50. 05003 Ávila, Spain. Tel:+34920353500, Fax: +34920353505 (manolope@usal.es)
2 Research Group of the Seminar of Protohistory and Archaeology. University Rovira i Virgili of Tarragona
1

Received: 03/03/2016
Accepted: 20/04/2016

Corresponding author: Pérez Gutiérrez (manolope@usal.es)

ABSTRACT
In the fourth century, a new settlement was built over an ancient pre-existent building (eighth century BC),
situated in the top of a hill and associated to an emerging aristocratic system which is presumed to have
disappeared at the end of the Early Iron Age. This new settlement is, nowadays, kwon as La Gessera and
was first excavated over a hundred years ago .
Located in the western side of the modern day province of Tarragona, this building, with a hexagonal
floor plan, covers the entire rocky surface, making it an unassailable fortress, and allowing it to control a vast
amount of the surrounding area, especially from and to the Ebro River. Nevertheless, the unusual floor plan
of this building, combined with the lack of water and the inability to collect basic resources, suggests that
this construction was more than just a simple house. In that case, it could be seen as a special place, even
though we still do not know what the building was used for.
Perhaps, the astronomical orientation could lead us to think it is remarkable. The well-known preference
for orientating significant buildings towards significant astronomical events is also to be found here. The
orientation of the main axis points unambiguously to the Equinoctial Sunrises, and it also coincides with the
corridor that goes through the building from east to west. Besides, the biggest and most remarkable room in
the building looks to the west. What is more, the seemingly unnecessary thick wall could easily have been
used as an altar. The apparent lack of straightness of the corridor could be perfectly explained by observing
the sunlight of the Equinoctial dawn. Only on those two particular days does the winding corridor allow the
sunlight to illuminate the room to which it leads.

KEYWORDS: Iberian Culture, Cultural place, solar orientations, Equinoxes.

292

1.

PÉREZ-GUTIÉRREZ et al.

INTRODUCTION

La Gessera (in Catalan, place formed by gypsum)
is an archaeological site located at the top of a rough
hill which can only be accessed from its north face.
From this spot a stretch of the Algars river basin can
be seen, as well as other important Iberian and coetaneous settlements like the village of Sant Antoni de
Calaceit and one of the road axis which might have
connected this site with the important village of Coll
del Moro in Gandesa (Moret, 2002: 165). Even
though Joan Cabré and Santiago Vidiella did some
explorations there between 1902 and 1903, it wasn’t
until 1914 that it was almost fully excavated under
the direction of Dr. Pere Bosch Gimpera (Bosh
Gimpera, 1915). Some of the materials extracted during the excavation work carried out in October 1914,
were taken to the Museu Arqueològic de Catalunya
(Archaeological Museum of Catalonia), and were
checked by Enric Sanmartí Grego (Sanmartí Grego,
1975a, 1975b) during the first half of the 1970’s. Later, another set of materials, together with the structures preserved in situ, were re-examined by Pierre
Moret (Moret, 2002) in 2000.
La Gessera is a protohistoric settlement included
in a territory with a broad and rich archaeological
heritage (Bea, 2012; Moret et alii, 2006). In fact, the
potential of the Matarraña-Algars area was already
recognized by the scholars of the early twentieth
century, who turned it into one of the pioneering
archaeological areas at state level with regard to the
systematic excavation, using archaeological techniques that can be considered modern.
The archaeological works carried out by the Institut
d’Estudis Catalans (Catalonian Studies Institute) focused on the region of El Matarraña, with some excavations in La Terra Alta, and the works in Caseres
(where our settlement is located) were finished in the
same year, 1914; once Bosch Gimpera considered that
the settlement of La Gessera was exhausted.
As a result, La Gessera fell into oblivion, just being occasionally mentioned in some scientific essays.
Then, a century later, the restoration and the museological conservation of the settlement and the reexcavation of some levels abandoned by Bosch
Guimpera were assigned to the Grup de Recerca del
Seminari de Protohistòria I Arqueologia de la Universitat Rovira I Virgili (GRESEPIA-URV) by the
council of Caseres.

2. LA GESSERA: THE BUILDING
If we look at the site from an urban point of view,
two distinct periods can be identified. The first, and
older, period dates from the Early Iron Age (late 7th
century and 6th century BC) and the second from
Iberian times (4th to 3rd century BC). Between these

two periods it was uninhabited, having been peacefully abandoned. It is important to note that there
are no signs of violence that may have forced the
inhabitants to leave the area.
Although the position of the walls and the stratigraphic relationships help us see the two different
periods in which the site was inhabited, the results
we obtained, particularly in reference to the later,
Iberian period, are no more than partial. This is because we are dealing with a site that had already
been excavated prior to our excavation of 2014. Such
“re-excavation” causes difficulties of interpretation
as we no longer have all the information necessary to
be more precise.
However, a credible level of interpretation leads
us to believe that during the Early Iron Age the site
was used as an isolated aristocratic residence, possibly imitating the “house / tower” models of occupancy, so prominent at that period in the areas of La
Terra Alta, El Matarraña and El Bajo Aragón. Although our knowledge of this phase is only partial as
we do not have a full topographical survey, at least
we can talk about two distinct areas, each being
more or less quadrangular and organized in a defensive system, based on the construction of orthostatic
walls.

Figure 1. Dron view of La Gessera

If we focus on the Iberian period [Σ1](IV-III BC),
using the data which we do have, we can rule out
the possibility that we are dealing with a conventional dwelling. One reason for this is the lack of evidence of normal domestic chores. The lack of fires in
almost the whole site is of particular interest. In this
regard we can take into account the size, dimensions
and other references which Bosch Gimpera took,
relating to the discovery of ashes, which he believed
pointed to the possibility of a domestic dwelling in
this part of the site. It is logical to believe that the far
south west area of the site could have been used as a
domestic dwelling, while the rest of the rooms,
based on the long, tight dimensions and the small
size, must have been used for storage or other, as yet
unknown functions.
Another peculiarity refers to the western extreme
of the site which is not only the largest area in use (9

Mediterranean Archaeology and Archaeometry, Vol. 16, No 4, (2016), pp. 291-295

293

LA GESSERA: AN IBERIAN BUILDING FOR WORSHIP?

m2), but also, in the second urban period it breaks
the parallel pattern of the southern areas of the site
by adopting an irregular polygonal form and taking
up the space that would otherwise be part of the central corridor. We will look at the layout of this area
later in the paper, along with its dimensions in relation to the rest of the site.
What marks this area out for particular investigation
is, among other things, the fact that this is the area of
the site where we have found most ceramic remains
from the Iberian period. 11% of all the ceramic
remains in the site were found in this one area[Σ2],
even though there are no pieces or specimens which
can be said to belong to any individual part of the
site. It is also interesting to note that this is also the
area where we have found most carpological
remains, for example a caryopsis of pine (Pinus
halepensis), one of a vine (Pinus halepensis) and
another of a lentil (Lens culinaris).

Figure 2. Topographic survey of La Gessera[Σ3]

3. DIGITAL RECONSTRUCTION OF THE
BUILDING AND ITS ENVIRONS
The digital reconstruction, necessary for the solar
simulation of the topographic area of the hilltop (La
Gessera) was carried out as follows (Figure 3). We
started with the official map of the area (the official
1:10.000 map produced by the Catalonian Cartographic Institute), from which we separated the information from the hypsometry, represented by 5
meters hypsometry curves of which gave us an outline. The points which define the contour lines were
then used to calculate the Triangular Irregular Network (TIN), which in turn allowed us to make a Digital Terrain Model (DTM).
The orientation of the map was corrected using
the convergence of meridians (the difference between the UTM grid north and the geodetic north,
which for our needs is the same that as the astronomical one.
The building has been digitally reconstructed,
based on a highly detailed topographic survey

(Figure 3). This digital model has been oriented astronomically on site, using the habitual meridian determination for the resolution of position triangle
with the Sun. This technique is explained more clearly in Pérez Gutiérrez 2014a[Σ4]).
Both models have jointly been incorporated in a
CAD (Computer-Aided Design). Thus it is possible
to simulate the entrance of sunlight into the building, as we can see in the next paragraph[Σ5].

4. GEOMETRY AND ASTRONOMICAL
ORIENTATION IN THE BUILDING
The first peculiarity to take into account is the
ground, which is hexagonal and symmetrical to the
north–west axis[Σ6]. The western wall maintains this
pattern and follows the north south direction. This
indicates that that the corridor which goes through
the building does so in an east–west direction. It
must also be said that the principal orientation of the
building is equinoctial as the height of the horizon is
very low in either direction[Σ7].
However, a detailed survey of the structure of the
building, leads us to the central corridor. Unlike the
other walls in the building, these walls go in a winding track and at first sight, seem to be badly built. In
these difficult conditions it is very difficult to ascertain the exact direction or orientation of the corridor.
It is here that the 3D digital reconstruction comes in
to its own.
In fact, when talking of orientation in a building
or other structure, we need the exact definition of a
direction (the astronomical azimuth) which is always
calculated from a straight line which goes through
the axis and connects the observer to a point on the
horizon in which an astronomical phenomenon takes
place (is verified). It is usually the twilight of an important star such as the sun, the moon or any of the
brightest stars in the sky. If we apply this principle
to our case, we are forced to determine a “middle
axis” of the corridor which would give us, as we
have already mentioned, an “approximately” equinoctial orientation.
However, we could easily go a little further into
this subject by trying to answer the following question: “Why is this particular corridor not made of two
straight parallel walls like the rest of the building”?
We could start to answer this question by going
back to the room at the end of the corridor. This
stands out because of its size, form and usage as we
have said before. It is the only room in the building
which can receive solar light through the corridor,
which we can assume was covered like the rest of
the building, even though iIn Figure 4 it is open to
the elements. The reason for this could be that it lets
light into the corridor and thence into the room at
the end of the corridor..

Mediterranean Archaeology and Archaeometry, Vol. 16, No 4, (2016), pp. 291-295

294

PÉREZ-GUTIÉRREZ et al.

Figure 3. Phases of process of DTM reconstruction

The entrance of sunlight is critical, especially as it
has been shown that light only gets into the room on
two days per year – the equinoxes[Σ8]! This can be
seen in Figure 4, where we are able to see the inside
of the room where we can see a small part of the
room at the back, lightened from the sun coming in
from the corridor. We are now able to answer our
question. The bends and turns in the corridor, to-

gether with the small entrance to the room, limit the
amount of sunlight that can reach the back of the
building where the room is, except for a brief moment at sunrise two days per year. After that short
moment, due to the length of the corridor, the sun is
no longer able to enter the room again for another 6
months. En la

Figure 4. The entrance of the sunlight through the corridor lighting the back room. Bottom left, view from inside the
room

5.

CONCLUSIONS

In summary, we are dealing with an isolated
building which, during the Early Iron Age, was used
as a house by an emerging aristocracy (system that
collapsed afterwards, Bea, 2012). It was rebuilt during the Iberian period and it had a use that, even
though it is still unknown, shows strong evidence of

the astronomical orientation associated with cult
sites and sanctuaries.
Throughout the Iberian territory, from the north of
the Mediterranean coast to the mouth of the Guadalquivir river in the Atlantic ocean, this pattern of orientation can be seen in a multitude of cult buildings,
such as the temple of El Tossal de Sant Miquel de

Mediterranean Archaeology and Archaeometry, Vol. 16, No 4, (2016), pp. 291-295

LA GESSERA: AN IBERIAN BUILDING FOR WORSHIP?

Llíria in Valencia (Esteban 2006) and the sanctuary of
Puente Tablas in Jaén (Pérez Gutiérrez et al. 2016).
The equinoctial orientation is also important in
topographic indicators on the horizon as seen in El
Amarejo in Albacete, La Serreta in Alicante and La
Carraposa in Valencia, among many others (Esteban
2002[Σ9]). And even in necropolis (in this case using
the sunset as is usual in Iberian sites dedicated to the
cult of the ancestors) like for instance, in the most

295

important funerary chambers of Tútugi in Granada
(Pérez Gutiérrez & Rodríguez Ariza 2014).
Although it is not completely proven, the astronomical orientation of the site and the way it is produced, makes it inevitable that we ask ourselves if
La Gessera was an Iberian sanctuary. We still cannot
answer that question with absolute certainty but we
hope to do so in the future.

REFERENCES
Bea, D. 2012: Poder, arquitectura i complexitat social. Formes polítiques al curs inferior de l’Ebre durant la
protohistòria. Tesis Doctorals en Xarxa (TDX). Universitat Rovira i Virgili
Bosch Gimpera, P. 1915: “Campanya arqueològica de l’Institut d’Estudis Catalans al límit de Catalunya i
Aragó (Caseres, Calaceit i Maçalió)”. Anuari de l’Institut d’Estudis Catalans, 5: 819-838.
Cabré, J. 1908: “Hallazgos arqueológicos”. Boletín de Historia y Geografía del Bajo Aragón. Vol. II, núm. 5:
214-244.
Esteban, C. 2002: “Elementos astronómicos en el mundo religioso y funerario ibérico”. Trabajos de
Prehistoria 59 (2): 81-100.
Esteban, C. 2006: “Ciclos de tiempo en la cultura ibérica: la orientación astronómica en el templo del Tossal
de Sant Miquel de Llíria”. Trabajos de Prehistoria 63 (1): 167-168
Moret, P. 2002: “Tossal Montañés y La Gessera: ¿residencias aristocráticas del Ibérico Antiguo en la cuenca
media del Matarraña?” I Jornades d’Arqueologia. Ibers a l’Ebre. Recerca i interpretació. Tivissa, 23
i 24 de novembre de 2001. Ilercavònia. Fulls d’Arqueologia, 3: 65-73.
Moret, P.; Benavente, J.A.; Gorgues, A. 2006: Iberos del Matarraña. Investigaciones arqueológicas en
Valdeltormo, Calaceite, Cretas y La Fresneda (Teruel). Āl-Qannīš. Boletín del Taller de
Arqueología de Alcañiz, 11.
Pérez Gutiérrez, M.; Ruiz Rodríguez, A.; Molinos Molinos, M. 2016; “The iberian urban sanctuary of Puente
Tablas (Jaén, Spain) (IN PREESS)
Pérez Gutiérrez, M; Rodríguez Ariza, M.O. (2014): Astronomy, Metrics, and Proportionality in the Iberian
Necropolis of Tútugi (Galera, Granada, Spain). Mediterranean Archaeology and Archaeometry, Vol. 14,
No 3, pp. 121-131
Sanmartí-Grego, E. 1975a: “Las cerámicas finas de importación de los poblados prerromanos del Bajo
Aragón (comarca del Matarranya). Cuadernos de Prehistoria y Arqueología Castellonense, 2: 87132.
Sanmartí-Grego, E. 1975b: “Algunas observaciones sobre el kylix de La Gessera”. XIII Congreso Nacional de
Arqueología (Huelva, 1973). Saragossa: 756-759.

Mediterranean Archaeology and Archaeometry, Vol. 16, No 4, (2016), pp. 291-295