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Roman coins

The Gallo-Roman Museum has a large collection of Roman coins: more than 6,500 in total. Almost all of them were found in and around Tongeren. That’s what makes them so valuable. They teach us a lot about the regional economy in Roman times.

The museum has set up a project to better register the coins and to photograph them one by one, in order to make them accessible online. We will provide the data in an ‘open’ format. This way, everyone can freely download and use the data and photos. We received subsidies from the Flemish government for this extensive project.

You can follow the progress of the project below.

We submit a project application to the Flemish government to obtain subsidies for an extensive catch-up operation with regard to the digital registration and accessibility of our collection of Roman coins.

Jan Jambon, Flemish Minister of Culture, awards us a project subsidy of 35,000 euros for the realization of our coin registration project. Let’s get started!

Due to the outbreak of the corona pandemic in the spring, our project was delayed for several months, so we had to adjust the schedule.

In parallel with this, we developed the project plan we had submitted to the Flemish government into a concrete action plan. We are committed that the description, storage and publication of our data will comply with international FAIR principles. FAIR stands for ‘findable’ (findable), ‘accessible’ (accessible), ‘interoperable’ (exchangeable) and ‘reusable’ (reusable).

We start by adding information about the locations of the coins to our collection database. We also link the names of the sites to an online database of place names (GeoNames). For example, our data becomes what is known as ‘linked open data’. Once they are online, they will become a lot more accessible, also for non-native speakers. To find the exact locations in Tongeren and the surrounding area, we delve into our archive with old inventory books, records and publications.

An important moment. An outside photographer starts photographing the more than 6500 coins. The photography is done in the museum with specialized equipment. This makes it possible to work up to ten times faster than if we were to shoot in the traditional way.

The 6506 coins are photographed on both sides. In total, this amounts to 13012 photos. The project is on schedule. We save the photos in both tiff and jpeg format. We also have 6506 combination photos. These show the front and back of each coin side by side. These will be used for the online presentation later.

Our collection database contains information about the weight, diameter and die alignement (that is, the orientation of the front and the back relative to each other) of the coins. They were registered decades ago. A sample with a precision scale shows us that the weights mentioned are not sufficiently reliable. It also appears that the same method was not always used to determine the diameters and the die alignements. Conclusion: we have to measure, weigh and study every coin again. This was not foreseen in the plan.

We link the terms we use in our collection database to describe the coins with terms in the databases ‘Nomisma’ and the ‘Art & Architecture Thesaurus’. This involves concepts such as coin names (e.g., sestertius), techniques (e.g., minted), materials (e.g., gold) and mint workshops (e.g., Rome). This link makes it possible to publish the data about our coins online in the form of ‘linked open data’ at the end of the project. In this way, we can make them accessible worldwide.

An external coin specialist starts checking, correcting and supplementing the description and dating of the coins. Is it a gold, silver or bronze coin? Is it a denarius, a sestertius, an as…? Which emperor issued the coin? In which coin workshop and in which year did that happen? What is depicted on it and what text can be read on it?
She also links our coins to the coin types of the ‘Online Coins of the Roman Empire (OCRE)’. This is a ‘linked open data source/database’. It is an international catalogue of all 43000 known coin types from the Roman imperial period.
The expert mostly works from home. This is perfectly possible thanks to the detailed coin photos that we recently obtained.

A brief status report in figures. The external coin specialist has checked and completed the description and dating of 24% of the coins photographed. We have checked the weight, diameter and stamping position of 27% of the coins. We have already linked about 44% of the coins to a location in the online database ‘GeoNames’.


We successfully imported the approximately 6,500 combination photos of the coins into our collection database. We will display the photos, showing side by side the obverse and reverse of each coin, online.


Julie Van Roy is a guest at the museum. As part of Archaeology Days, visitors can talk to subject specialists. Julie demonstrates how to identify Roman coins. She gets a lot of interest from our visitors.


Coin specialist Hugo Vanhoudt photographs an additional 300 Roman coins. These are mainly specimens from the time of the Roman republic, but also a number of imperial pieces not yet registered in our collection database last year.


We successfully imported the some 300 combination photographs of the additionally photographed coins into our collection database. Julie Van Roy will also review these coins. She will link the republican coins to the coin types of the database Coinage of the Roman Republic Online (CRRO).


Julie Van Roy has reviewed all Roman coins in our collection database and corrected, completed and linked about 4300 specimens to the coin types of OCRE or CRRO. Her task has been completed. The remaining coins are not sufficiently well preserved and not legible enough to identify the type. They are therefore less interesting to display online.


We have greatly expanded our collections site Exploratorium. In addition to some 150 masterpieces, from now on we will also display more than 5,500 other objects from our collection, including a first set of 500 Roman coins. An important step for our coin project! These are the coins whose registration is completely up to date. They have been photographed, checked and improved by the coin specialists. Their weight, diameter and stamp position have been verified and they have been linked to their find spots. We will show the remaining coins online later, once that research is also finished.


Our colleagues at the Musée départemental Arles antique in France are producing a new catalogue of all the coins minted in the Roman mint workshop of Arles, ancient Arelatum. Some time ago, they asked us if we have any in our collection. Thanks to our coin registration project, we were indeed able to identify 216 specimens minted in Arles. We gave priority to finishing those coins and shared the data and photos with colleagues from Arles. From now on, the coins can also be seen on our collections site Exploratorium.


Originally, our coin registration project was supposed to be completed by the end of 2021. Unfortunately, this is not yet the case. Because the Flemish government is subsidising the project, we did submit an administrative justification file and ‘final report’ in the meantime. Of course, we will continue to complete the project as planned.


We now display 1075 Roman coins on our collections site Exploratorium. Of the remaining coins, we still need to verify the findspot and/or the weight, diameter and stamp position.

Igor Van den Vonder
coordinator collection management/registrar
+ 32 12 67 03 64