Studying changes in medieval urban fabric comprises collecting all the available data on preserved and unpreserved parts and using them to reconstruct what was lost while understanding the processes of changes that occurred over centuries.
This paper presents a model for structuring and interpreting information on a medieval city and its changes. Its purpose is to support future hypotheses, and the final result aims to serve as a prototype for similar urban studies.
The city that has been studied is Trogir, located on a small island on the eastern Adriatic coast. The urban fabric, built in stone, covers the whole surface of the island and testifies to more than two thousand years of continuous urban life. Due to the excellently preserved medieval and early modern buildings, Trogir was declared a UNESCO World Heritage Site in 1997. On its edge, the buildings that stand out are two High Medieval and one Renaissance tower, the Late Medieval castle and a portion of the city walls, which are only a lesser part of the former fortifications that protected the city.
The time scope of the model covers seventeen centuries – from the foundation of the ancient Greek colony around 220 BCE until 1500 CE. A Hellenistic tower has protected Trogir’s SE part for over two thousand years. From 220 BCE until 1420 CE, the city expanded several times. Afterwards, only modernisation of the defence system occurred. Little is known about the Hellenistic, Late Antiquity and Early Medieval fortifications. Information on the fortifications protecting the city from the High Medieval and Renaissance periods is also fragmented. The author believes the model would make it easier to understand how fortifications from these earliest periods were first incorporated and then disintegrated within the urban fabric as the city expanded. The model consists of a base map, seven layers, each for a different source type, and a layer for the hypotheses.
This study’s principal source is the urban fabric, comprising fortifications preserved at full height or only in parts above the street level. All known information is collected and presented in the first layer using georeferenced architectural drawings and plans. The second layer offers all information on remains unearthed in archaeological campaigns. They are mapped using the same method as in the first. A critical analysis of historical maps and blueprints, based on the precision by which they were made and the information they provide, led to a selection of just a few. They provide information on buildings that are not preserved in the urban fabric. This information is presented in the third layer after georectification. Information on the form of dismantled parts of the fortifications, provided in old photographs, is delivered in the third layer. The next, similarly, offers those from critically analysed vedute (historical cityscapes). Information from these visual sources, presented in the third, fourth and fifth layers, provide only quality information on the no longer extant buildings. The last two layers contain information from written sources: late medieval archival documents, consisting predominantly of notarial acts (preserved in fragments from 1263 until 1500), and local historiographical text. These textual sources provide information on the former existence of different parts of the fortifications, on construction, builders and commissioners of both extant and no-extant parts of the fortifications, and on their owners and tenants and the way they used it, revealing thus details on their former forms and changes.
In the first three layers, polygons are used to reveal the perimeters of the buildings or the width and length of the parts of the walls. In the following two layers, the facades of the fortifications, visible in sources, are presented in lines as projections. Texts are presented with points; each document or information from a historiography book is a separate entry. The colours represent periods during which a portion of the fortifications had been constructed, and they are applied to all inserted symbols. The periods are Hellenistic (around 220BCE), Late Antiquity (4th to 7th century CE), High Medieval (before 1200, predominantly the 12th century CE), Late Medieval (between 1200 and 1470 CE), and Renaissance (after 1470 CE).
Each inserted symbol is provided with an annotation. First, there is metadata: ID number, name of the building, state of preservation, period (which resembles the periods presented with colours), date of the construction, when available, and reference to a publication. Second, there is a short description of each source and an explanation of the data it provides. In cases of ambiguities, a method of dealing with it is explained. It differs from source to source and data to data, offering interpretation within the limits of argumentation. Third, each annotation is provided with an illustration of a source and the caption. Archival documents are supplied with photos, transcription of the relevant part and a regesta (summary). In the seventh layer are illustrations of the historical book pages. They are written in Latin or a local idiom of Italian, so summaries are added.
The layers overlap and are transparent, and they are laid over a base map representing contemporary urban built fabric in 2024. Together, they demonstrate the existing information on the fortifications and the limits of our knowledge.
This methodology of using all the available data from all kinds of sources already led the author to hypothesise on the former site of a portion of the High Medieval city walls and a tower. The hypothesis was published in 2007 and has been accepted by other scholars studying Trogir. This hypothesis is presented in a separate layer, using dashed lines to distinguish it from the different symbols. The dashed line’s width resembles the width of the High Medieval walls, which are known from the preserved remains. The author expects the model to lead to new hypotheses about the locations of the fortifications that decayed over centuries (especially the Hellenistic, Late Antiquity and High Medieval ones) and to formulate principles of their changes and integration into the urban fabric.