Cologne

Relics said to be those of the magi were taken from Milan to Cologne in 1164 by Rainald of Dassel, archbishop of the city and chancellor to Frederick Barbarossa, after the emperor had taken Milan by force. The transfer was a political act as much as a devotional one: it gave the archbishop of Cologne the bodies of the first kings to acknowledge Christ, at a moment when the empire and the papacy were in open conflict over who crowned whom.

The goldsmith Nicolas of Verdun and his workshop built a reliquary for them in the decades around 1200, in the form of a basilica in gilded silver set with several hundred antique gems and cameos, the largest such shrine in Europe. Pilgrims came in numbers the existing cathedral could not hold, and in 1248 the chapter began a new one, on the French Gothic model, expressly to house it. Work stopped in 1560 with the choir finished and a crane standing on the unfinished south tower for three centuries; the building was completed to its medieval plans between 1842 and 1880.

The shrine remains behind the high altar. Its presence gave the city an Epiphany feast of national importance, gave German households the custom of chalking the initials of the three names above a door at the new year, and left the cathedral as the reason the city was rebuilt around a church that survived the bombing of the surrounding streets in the Second World War almost alone.

In 1248 the Dominicans established a general house of studies at Cologne and put Albert the Great in charge of it. Albert's project was to make the whole of Aristotle available and intelligible to Latin readers, natural science included, at a time when much of that corpus was suspect. He wrote on minerals, plants and animals from observation as well as from texts, and he taught that the study of nature and the study of God were not rivals. Thomas Aquinas was among his students in the city, and Albert is buried in the crypt of St Andreas beside the cathedral, where his tomb is still visited.

Seven centuries later the university acquired an object of a different kind. The Cologne Mani Codex is a Greek parchment book of the fourth or fifth century, remarkable first for its size: the written page is smaller than a matchbox, among the smallest codices known. Its text is an account of the youth of Mani, the third century prophet whose religion spread from Mesopotamia to China, assembled from the testimony of his early disciples.

Its importance is that it describes the community Mani grew up in, a Jewish Christian baptist sect practising repeated ritual washing, and his break with it over the claim that purity is a matter of what enters the body. Before the codex was read, Manichaeism was known mainly through the polemics of its enemies, Augustine among them. The codex let it be studied from the inside, and it sits in a university library in a city best known for a cathedral.