A medal was struck to commemorate this event, with the legend: HÆC REGIS REGUM TOTO PRETIOSIOR AURO, and S. Louis kneeling before an altar upon which is the crown of thorns. As to the particular tree of which the crown was composed, there was much difference of opinion. Clement of Alexandria calls it _ex rubo_, a sort of thicket; other writers a different sort of shrub or bush, called _nerprun_, or wild plum; and others, the white thorn.
The antiphon used every day in the offices of the Sainte-Chapelle began: _Ecce Crux et Corona Spinea Arnia Regis Gloriae tibi commendantur_; and the seal consisted of a cross with the crown of thorns intersecting it, and on each side a _fleur-de-lys_, with the King's crown at the top. Having acquired the holy relics, it was most seemly that a shrine should be constructed wherein they should rest--a shrine worthy the sanctity of such treasures. And so S. Louis commissioned his architect, Pierre de Montereau, to build him a chapel which should be a marvel of lightness and colour, embellished with windows which should glitter like precious stones, and containing a _châsse_, resplendent with enamels, and gold and silver--a shrine, as it were, within a shrine. That the architect was worthy the confidence of his royal master, the chapel testifies to this day, and Maître Pierre's immortal work remains the most perfect example of 13th century architecture in France; one might say, the most exquisite architectural gem which the world has yet seen, or is ever likely to see.
Pierre de Montereau, or Montreau, as it is sometimes written, lived eighteen years after the completion of his _chef-d'œuvre_, and doubtless assisted at some of the splendid ceremonies held in it. He died March 17th, 1266, and was buried in the chapel of the Virgin belonging to the religious of S. Germain des Près, where a splendid monument was erected to his memory. Some of the finest of the buildings attached to the monastery were his work, and up to the last century a stone was to be seen over his burial-place, upon which he was represented with a rule and compass in his hands. His epitaph gives him the titles of _fleur pleine de bonnes mœurs_, and of _docteur des architectes_: