The Gothic collegiate church of St. Nicholas in Freiburg features some of the most beautiful Art Nouveau stained-glass windows in Europe. They were created by Joseph Mehoffer from Cracow, who in 1895, at the age of 25, impressively won the international competition for the design. The execution of the work continued over the subsequent 40 years.

The enormous stained-glass panels (up to 12 m high) are placed in the tall Gothic pointed-arch windows of the chapels opened to the aisles (1895-1918) and of the chancel (1919-1936). They depict the Holy Trinity, the victorious Mother of God, episodes from the Gospel, e.g. Adoration of the Magi, the Apostles, the saints worshipped in Freiburg and scenes from the history of the city.

The figural scenes are interwoven with fragments of architecture and landscape, as well as ornamental floral motifs. They sparkle kaleidoscopically, changing colors in the sunlight, which takes the architecture of the cathedral into a different dimension and at the same time gives it a coherent character. The stained-glass windows were created over the period of 40 years and reflect the artistic transformations of the times - from the end of historicism, through the successive phases of Art Nouveau (aisle chapels), to the designs close to art déco (chancel).

It is one of the largest stained glass cycles in modern art. Its distinguishing feature are the spectacular lighting effects inside the church resulting from the artist’s excellent understanding of the material and his remarkable skill in working with stained glass. The poetic iconographic inventiveness, decorative style and, above all, excellent craftsmanship made these stained-glass windows one of the most interesting works of European Art Nouveau, enthusiastically received not only in Switzerland but also in the whole of Europe.

In the wake of this success Józef Mehoffer received other commissions to make stained-glass windows, including the ones for the church in Onnens (1902) and in the chapel of the Grauer family in Opava (1901), as well as the polychromes, stained-glass windows and paintings in the Church of the Sacred Heart of Jesus in Turek (1930-1939). He also designed stained-glass windows for the Latin Cathedral and made the polychrome on the vault of the Armenian Cathedral in Lviv.

The drawings of the designs of the Freiburg stained-glass windows made on immense sheets of paper can be seen in the National Museum in Cracow.