Alchemical connections

Charles IV built the castle between 1348 and 1358 as a repository for the Bohemian Crown Jewels. It was meant to evoke Montsalvat and the Temple of the Holy Grail. The Chapel of the Holy Cross, on the Great Tower's third floor, is lined with 2,392 precious stones: carnelians, agates and jaspers. Only recently, according to the source, an amateur geologist accidentally rediscovered the Erzgebirge deposit of agates used in the decoration. A niche above the masonry altar held relics of the Holy Cross and other imperial treasures. Charles was an avid relic collector. The inventory lists a piece of the manger, a tooth of St John the Baptist, part of St John the Evangelist's robe, St Anne's arm and links of the chains that bound Saints Peter, Paul and John, all set in gold and silver reliquaries. There were also part of the Last Supper tablecloth, thorns from Christ's crown, and Charlemagne's sceptre and sword. Other relics were placed in walls, picture frames and windows. Although Charles himself probably devised the concept, the painter-alchemist Theodoric realised the spiritual transformation of light, sacred images and the chapel's inlay. To create the desired vision of the city of light, the ‘heavenly Jerusalem’, the source argues, artistic training alone was not enough: alchemical practice was essential. The solar cult is celebrated through the close link between gold and the Sun. The Sun and Moon occupy a prominent place among the stars on the vault. Their union is often accompanied by an eagle, an image of the world spirit. Charles therefore had the legend of St Wenceslas painted on the staircase to the chapel, expressing a connection between the imperial eagle and St Wenceslas's eagle. Thick gemstones originally filled the windows instead of glass, so the interior was lit by hundreds of wax candles representing God, the ‘light of the world’. The emperor came here to be ‘enlightened’.