De ecclesiola in het Utrechtse castellum. Bouwhistorische interpretatie van de resten van de Heilig-Kruiskapel
The 're-excavation' in 1993 of part of the foundations and above-ground walling of the Heilig-Kruiskapel has revealed new data with respect to the history of its construction. The most important conclusion is that the southern annex of this chapel was a separate unit and as such it was the seventh-century predecessor of the church attached to it later. It is likely that the Heilig- Kruiskapel itself is to be identified with the St Maarten's church built by Willibrord.
This hypothesis on the basis of architectural-historical findings implies that a new architectural structure is to be added to the structure at Dom square in Utrecht we are already acquainted with, a small church which so far had only been known from written sources and the location of which was conjectured to have been outside as well as inside the Castellum. The site and size of the first Christian foundation in Utrecht now localized raise new questions on its original function.
In view of its small size the square chapel or cella may have been a burial chapel or cella memoriae. The existence has been proved of early-medieval burials in stone sarcophagi in and around the earliest Salvator church in Utrecht, which probably date back to the eighth and ninth centuries. More deeply situated burials in wooden coffins could be part of the oldest Christian burial place.
Unfortunately, the medieval burials in and around the Heilig-Kruiskapel have not been researched accurately enough to be able to refer to them as early-medieval burials with any certainty. A number of burials in wooden coffins, just as similar burials around Salvator church situated at a rather large depth and appearing to be somewhat grouped into two strips to the east of the Heilig-Kruiskapel, possibly are among the oldest Christian tombs.
The niche in the eastern wall must have had a funerary function in the use of the place as a burial chapel. Although the internal dimensions of the niche are rather small, one may think of the lay-out of a tomb as ‘arcosolium’ or niche tomb, possibly with an altar placed in front of it. A cella memoriae can also be interpreted in another meaning: the memoria may refer to the presence of one or more relies. At any rate, from the sixth century onwards each altar was provided with at least one relic.
Particularly for a Christian outpost in an area which had to be converted, the presence of a relic may have been an important condition for the success of missionary activities. The question which relic was already present in Utrecht in the early seventh century, however, will have to remain unanswered for the time being. In view of the consecration at any rate in the time of Willibrord, a St Maarten's relic is most likely, but an original consecration to Thomas Apostle is also possible; however, in this respect the Utrecht tradition is very late.
The scarce data on the earliest Christian history of Utrecht are to be supplemented with the foundations and part of the aboveground walling of the first little church in the castellum, referred to as ecclesiola by Boniface. However, all sorts of questions on its use, consecration and incorporation in the later episcopal cluster of church buildings remain unsolved as yet, and it will only be possible to answer them after closer research.