New insights into urban planning of Caricin Grad: The application of modern sensing and detection methods
Authors: Ivanisevic Vujadin , Bugarski Ivan , Stamenkovic Aleksandar 
Published: January 2017

Caricin Grad, Justiniana Prima, urban planning, fortification, settlement,
aerial photography, geophysical surveys, LiDAR, photogrammetry, excavations,
GIS. Thanks to the application of modern non-destructive sensing and
detection methods, in recent years a series of new data on urban planning in
Caricin Grad was obtained. For the most part, the current research programme
studies the Upper Town?s northern plateau, wooded until recently and hence
the only previously unexplored unit of the city. In the course of this
programme, the classical research method - the excavations started in 2009 -
is for the first time combined with the systematic application of airborne
and terrestrial sensing and detection techniques. The analysis of historic
aerial photographs and topographic plans proved to be very useful as well.
Along with them, LiDAR-derived DTMs, photogrammetric DEMs, different
geophysical and orthophotographic plans are stored in the GIS database for
Caricin Grad and the Leskovac Basin. In this way almost 80 percent of the
plateau area was defined, and the obtained plan is hypothetical only to a
small extent, which particularly refers to the unexcavated northern rampart
of the Upper Town. Each source provided relevant information for the
reconstruction of both the rampart and the settlement, which points to the
value of a holistic approach to documentation from various dates. The first
source to be studied were archival aerial photographs of Caricin Grad from
1938 and 1947 (Figs. 1, 2.1). The latter one was originally processed by
Aleksandar Deroko and Svetozar Radojci}, who drew the plan of the town after
it, labelling the unexplored Upper Town?s northern plateau as ?a probable
habitation area?. The route of the northern rampart was aslo rather precisely
determined by the authors (Fig. 2.2). Recently, these photographs were
rectified and georeferenced in the GIS. The 1938 shot reveals the position of
some towers as well, and it is also indicative of the way of construction of
certain buildings. From the spatial layout of whitish zones, originating from
mortar scattered along the slope, it can be deduced which buildings were
constructed in opus mixtum - the horreum and the so-called Building with
Pillars east of it. Traces of mortar can be observed along the route of the
rampart too. These archival images are particularly important because they
record the topography of the site before it was filled with heaps of earth
from the excavations. The topographic mappings of this area were conducted in
1981 and 2006 (Fig. 3). The first plan was drawn after an airborne
stereophotogrammetric survey of Caricin Grad, and in 2006, after the wood was
cut down, this whole area was surveyed with the total station, with a density
of nine points per square meter. This survey also resulted in a 3D terrain
model (Fig. 3.2) indicating the layout of the buildings, which was to be
proved by geophysical surveys and archaeological excavations. In the course
of the Serbian-French reaearch programme, in 2007 geomagnetic surveys were
carried out by Alain Kermorvan of the University of Tours. Thanks to the
application of this method the remains of collapsed stone structures could be
observed, and in 2015, in cooperation with the Roman-Germanic Central Museum,
Mainz, and the Ludwig Boltzmann Institute from Vienna, the middle and eastern
parts of the plateau were scanned with GPR (Fig. 4.2). Precise plans of the
buildings were obtained in the areas in which LiDAR scanning and
photogrammetric and geomagnetic surveys failed to produce clear images.
Within the framework of the ArchaeoLandscapes Europe project, in 2011 we
managed to organise an airborne LiDAR survey of the wider area of Caricin
Grad. With its density of some 20 points per square meter, this scanning
proved to be crucial for our comprehension of the town. The standard DTM
provided numerous important data, especially its version calculated in the
focal statistics function of the ArcGIS software package (Fig. 5. 1-2). These
models show not only the route of the Upper Town?s northern rampart, the
position of its towers and the layout of the buildings, but also the line of
the Outer Town?s western rampart. Visible only in the DTM, this entirely new
aspect of the Caricin Grad fortification has been attested by the
excavations. Highly important plans of the town, and of the northern plateau
of the Upper Town in particular, were obtained by UAV photogrammetric
surveys. The first drone survey was conducted in 2014 within the scope of the
same project. It resulted in a cloud with up to 1,600 points per square meter
(Fig. 6.1-2). Unlike the LiDAR technology, photogrammetry cannot penetrate
vegetation; therefore the preliminary clearing of the ground proved to be a
most important step. After the 2015 campaign was finished, the excavation
area in the Upper Town was documented again in the same manner. Regular
photogrammetric surveys make possible the control of the works and reliable
visual monitoring of the progress of exploration (Fig. 9). After the wood was
cut down in 2006 and enormous heaps of earth from twentieth-century
excavations and restoration works were carefully removed by machinery in 2008
and 2010, without disturbing the original layers of debris, wide excavations
could begin. At first only the humus layer was removed from fifteen-meter
squares, which was followed by technical drawing. In 2009 and 2010 we did not
explore the debris or the cultural layers (Fig. 7.1-2). The additional two
squares were opened and documented in the same fashion in 2011, when
previously recorded buildings 11 and 15C were explored in detail, together
with the part of the corridor between them where a bread oven was found.
These buildings were oriented south-north, cascading along the mild slope
towards the northern rampart of the Upper Town. Fragments of pithoi and
carbonised fruits were found in the buildings, allowing for an economic
interpretation. Judging by coinfinds, the buildings ended in fire after the
year 602. Some of the buildings on the northern plateau were oriented
differently, following the route of the northern rampart of the Acropolis in
the east-west direction. In 2012 building 18 was excavated, leaning on the
rampart. Rectangular in plan and some 12 by 7.5 meters large, it had a storey
and a 7 by 5.5 meters spacious paved atrium in the west. Parallel to building
18 is building 20, the only one on the northern plateau constructed in opus
mixtum. The two buildings are separated by a four-meter-wide street, running
from east to west. This street, corridor 4, was partly cut in the rock. In
some sections it had a substructure of fragmented debris. Building 20 has
been carefully excavated for several years now. After the initial
documenting, the surface layer of debris was removed, but not the collapsed
structures with characteristic construction details; to the east of the
building a collapsed wall was uncovered, containing as many as eight
successive rows of stone and brick. Beneath these layers are the occupation
ones, so far investigated only to a small extent. Building 20 is rectangular
in plan, covering 25 by 12.5 meters. In its central axis there is a row of
masonry pillars, dividing the building into two naves. On its western side
there was a vestibule with a pair of doors matching the main entrances to the
building. In the back of the vestibule, between these entrances and in axis
with the pillars, there was a staircase. Adetailed analysis of these features
led us to conclude that building 20 was a horreum, the first such edifice to
be discovered in Caricin Grad. Taking into account the details of its ground
plan, pillars, parts of collapsed walls and especially arches, it will be
possible to reconstruct the original form of the horreum. Judging by the
existing estimate, although somewhat rough, it was 13.5 meters high. It could
be observed that in its later phases the horreum was partitioned into several
rooms, and some of its entrances were walled up. In the vestibule only these
later occupation phases were documented, as the original brick pavement was
removed from its northern part. This was followed by a significant
accumulation of cultural layers, which were sealed by the debris stratum.
South of the horreum there is a spacious courtyard connected with the western
street of the Upper Town. The Upper Town?s northern rampart has never been
graphically reconstructed, despite the fact that Aleksandar Deroko and
Svetozar Radojci} published its accurate (although schematic) ground plan as
early as 1950 (Fig. 2.2). This part of the town has gradually been left out
of the research focus, mainly due to the vegetation growth. Upon employing
all the methods described above, however, it is possible to undertake such an
effort. The ideal reconstruction suggested here includes the rampart route,
the disposition and the form of the towers, and the possible locations of the
posterns. The line of the rampart can be traced following the trenches left
by the locals dismantling the walls. Only the section of the northwestern
rampart in front of the western postern of the Acropolis cannot be presented,
being still covered by massive earth deposits. On the other hand, the
recently discovered western rampart of the Outer Town can be traced to its
full length in the LiDAR-derived DTM. Its form can be easily reconstructed on
the basis of the results of the 2012 excavations and the section of the same
rampart uncovered east of the main fortifications in 1955-56 (Fig. 8). Having
studied the microtopography of the terrain, we were able to determine the
position of a number of towers. They were clearly indicated by bumps,
regularly distributed along the northern and northeastern sections of the
rampart. The position of the tower below the Acropolis? western postern could
be easily determined as well, unlike the position of the tower opposite to
the horseshoe-shaped one of the Acropolis fortification. Yet, it is hard to
imagine that a hundred-meter-long section of the rampart was left
unprotected. The rectangular shape of the towers is suggested because almost
all the towers of the town?s outer fortification were constructed in that
way. On the other hand, at present we cannot exclude the possibility that
some towers were different, horseshoe-shaped in plan, like the ones on the
Acropolis rampart. The disposition of the towers along the northeastern
rampart of the Upper Town, in the area where the northern street presumably
met the fortification, is not clear. This part of the site still lies under
massive heaps of earth, and even the 1938 and 1947 aerial photographs are not
indicative enough in this regard. However, the tower(s) might have been
erected there, not only because the eighty-meter-long stretch of the rampart
would be left without protection in an opposite scenario, but because it is
likely that the northern street ended in a gate, or at least a postern. It is
already known that some of the posterns on the Caric in Grad fortifications
were defended by towers. The average distance between the towers of the
town?s main fortification extends from 20 meters on the southern to 40 meters
on the western rampart of the Lower Town; in our reconstruction the average
interval on the Upper Town?s northern rampart is 44 meters. Another argument
is that this gate might have connected the Upper and the Outer Towns. The
position of the second postern is determined thanks to a depression in the
terrain following the axis of another communication route in the Upper Town,
leading from corridor 4 and running towards the north along the rows of
buildings. Finally, the 3.8 meter width of the rampart in the section
adjoining the northern tower of the Upper Town?s eastern gate may only
indicate a staircase, the last reconstructed fortification element. On the
plateau stretching between the northern ramparts of the Acropolis and the
Upper Town fortifications a settlement developed with its radially
distributed rows of buildings cascading down the slope. In the eastern part
of the plateau there is the horreum, adjoined from the east by another
building - the storage called Building with Pillars. Larger than the other
buildings and constructed in opus mixtum, the two buildings follow the route
of the Upper Town?s northern street, all of which indicates that they belong
to the initial construction phase. One should not exclude the possibility
that this part of the town was originally conceived as an economic district
with storages and similar edifices. By all appearances, the original concept
was soon abandoned. Already at the time of Justinian a settlement of numerous
smaller buildings was created. With their walls of stone and wattle and daub,
the buildings were roofed with tiles. Yet one should underscore that this
construction phase, although less sophisticated than the first one, was
accomplished according to a previously prepared plan; the spread of the
buildings speaks to that effect. Shortly afterwards, if not at the same time,
buildings were erected along the outer face of the Acropolis rampart - a
clear indication of abandoning urban planning (Fig. 9). Public space was
turned into private, in spite of the legal proscriptions of that time. During
the last phase of the town?s life the buildings described, whether public or
private, were partitioned into small rooms, often with fireplaces and with
some of their entrances walled up. Just like the edifices constructed in opus
mixtum, some of the more modest buildings from the second construction phase
were used to store food - namely buildings 11 and 15C. The plan of this part
of the site points to an organised settlement, most probably inhabited by
persons servicing a significant clergy and administration. On the other hand,
except for some houses - such as building 18 - small buildings along the
Acropolis fortification, facing the main street, corridor 4, might have
served as shops and workshops. Traces of furnaces, slag and bone working were
also encountered in this area. The parallel application of classical research
methods and modern techniques of sensing and detection enabled the
reconstruction of the northern rampart and the urban matrix of the Upper
Town?s northern plateau. Until recently among the least known parts of the
town, this unit can now be regarded as one of the best defined. This is
important not only for our understanding of Caricin Grad (Justiniana Prima),
but also for the study of Early Byzantine urban planning in general.