The beginnings of the Cologne bishopric go back well into the 4th century. The first known bishop. Maternus, was already mentioned in the earliest documents of 313-314 AD. In 1164 Archbishop Rainald von Dassel transferred from Milan the bones of the three Magi into the "older" section of the cathedral which was consecrated in 870. A precious reliquary shrine was ordered to house these relics and the work on it probably began during the reign of Rainald's successor Archbishop Phillip von Heinsberg.
These famous relics drew the faithful from all over Europe and the Cologne pilgrimage became one of the largest of the middle ages. For this reason the Cathedral Chapter decided in 1248 to build a new structre more suitable for such an important church. To accomplish this the chief architect did not did not turn to the Romanesque architecture of Germany but rather the more "modern" Gothic architecture of French cathedrals. But the measurements of the Cologne plan surpassed all other churches of its time.
Around 1265 the radiating chapels and ambulatory of this new structure were completed. By 1300 the East end was finished and consecrated in 1322. Various construction continued for centuries, through 1560. According to a 15th century document the Shrine of the Three Magi was to be placed in the crossing of the completed cathedral. It has been located in its current position since 1948.
The construction of the entire cathedral was completed during the 19th century. Friederich Wilhelm IV of Prussia laid a ground stone in 1842 as construction resumed again for the first time since 1560. By 1880 in the presence of Kaiser Wilhelm I, the last stone was placed atop the south tower. Some of the most important neo-Gothic works of art come from this period of the Cathedral's construction.