There is space in the Cathedral of St. Denis next to King Louis XVI and King Louis XVIII, but I think that it might be sometime before it is filled.
That surprises me. I was led to believe that Louis XVI's remains (along with those of Marie-Antoinette) were thrown into a mass grave along with hundreds of other victims of the revolution and never recovered?
Are you talking of an actual tomb for him or just a monument?
At the Cathedral of St. Denis there are the tombs of Louis XVI and Marie Antoinette in the crypt, and a monument to their memory in the church proper.
After the restoration of King Louis XVIII in 1814, he had the Chancellor of France lead an investigation into the exact location of the burials of Louis XVI and Marie Antoinette at the Madeleine cemetery. While their burials were not marked, it was not the same kind of situation as at the Picpus cemetery, where the remains of many nobles were thrown indiscriminately.
There were witnesses of the burials (including the priest who was present at the time) who testified to the locations, and particularly to the fact that the burials were at a lower level than the other burials (in order to avoid them being dug up by royalists). In the case of Marie Antoinette some clothing was found including two garters which were recognised as belonging to her (and perhaps even made by her). There was similar identifying evidence in the case of the remains of Louis XVI (silver shoe buckles, I think).
On January 21, 1815, the mortal remains of Louis XVI and Marie Antoinette were moved from the Madeleine cemetery to the Cathedral of St. Denis where they rest today awaiting the resurrection.
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