La collégiale Sainte-Gertrude de Nivelles. Réexamen du dossier archéologique

In 1940, the church of St. Gertrude of Nivelles was bombed and its roof destroyed by fire. The restoration work gave the opportunity to lead some archaeological research that brought to light its origins and the structures surrounding the mausoleum of Gertrude († 664). The present church has always been seen a homogeneous monument, the one which succeeded to the church burned in the early 11^th century and was consecrated in 1046. The development works, in and around the church between 2009 and 2011, led us to reopen the archaeological record of St. Gertrude. We found that the excavations of 1941 and from 1950 to 1953 had not been published extensively. New observations (using “stone by stone” surveys) were necessary to re-read the construction phases, and demonstrated that the current church keeps elevation parts that are anterior to 1046. At this stage of the study, we identify seven major phases, including the reconstruction dated 1046. The annular crypt, from the third phase, is one of the very first structures built in honor of the saint. The Westbau belongs to a different phase (V) still to be studied. The absolute chronology of the already identified phases has to be further clarified and strengthened by laboratory dating. However, the recent discovery of tiler kilns, at the foot of the Westbau, which last firing has been dated by archaeomagnetic method (around 940), could be put in relation with the construction of phase VI (the church destroyed by fire in the early 11^th century).