This paper will examine the south transept window of Cologne Cathedral, which was ceremoniously inaugurated in 2007 and realized according to a design by Gerhard Richter. The original window and its plans were irretrievably lost during World War II. Gerhard Richter, one of the most successful contemporary artists, redesigned it with colorful squares and by incorporating a principle of chance. Based on the artist's glass works and color panel paintings, the study will investigate whether a contemporary piece can harmoniously fit into the Cologne Cathedral, which was built according to Gothic ideals. The considerations aim to provide insights into the multifaceted work of the artist and offer intellectual impulses and inspirations in various directions. Finally, the focus will shift to the challenges of contemporary stained glass art in historical sacred buildings. Modern glass artworks by other artists in church buildings will be briefly presented before concluding with a summary of the key points of the paper.