Standing in the historic city of Aachen, western Germany, Aachen Cathedral is unlike any other church in Europe. At its heart stands an octagonal chapel built more than 1,200 years ago for one of history's most influential rulers, Charlemagne.
Over the centuries, generations of builders expanded the cathedral, adding magnificent Gothic chapels, soaring stained-glass windows, and one of Europe's finest medieval choirs.
The result is a remarkable building where multiple architectural eras exist in perfect harmony.
How did the personal chapel of an emperor become one of Europe's most important cathedrals?
Charlemagne's Vision
Construction of Aachen's Palatine Chapel began around AD 792 during the reign of Charlemagne, King of the Franks.
Inspired by the great churches of the Byzantine Empire, particularly San Vitale in Ravenna, Charlemagne sought to create a palace chapel worthy of a new imperial capital.
The octagonal central chapel reflected both Roman engineering and Byzantine artistic traditions.
Rich marble decoration, bronze doors, mosaics, and classical columns demonstrated the emperor's ambition to revive the glory of ancient Rome in Western Europe.
When Charlemagne died in 814, he was buried within the chapel that had become the spiritual heart of his empire.
The Coronation Church of Emperors
Following Charlemagne's death, Aachen became one of medieval Europe's most important ceremonial centres.
Between 936 and 1531, more than thirty German kings were crowned in the cathedral before travelling to Rome to be recognised as Holy Roman Emperors.
The cathedral therefore became closely associated with imperial authority throughout the Middle Ages.
Its marble throne, traditionally believed to have been commissioned by Charlemagne, remains one of the building's most important historical treasures.
For centuries, rulers ascended these steps as part of one of Europe's most significant royal ceremonies.
When Gothic Architecture Arrived
Although the original chapel was completed centuries before Gothic architecture emerged, Aachen Cathedral continued to evolve.
During the 14th century, builders added the magnificent Gothic choir known as the Glass House of Aachen.
Its enormous stained-glass windows rise almost the full height of the walls, flooding the interior with natural light.
The contrast between the solid octagonal Carolingian chapel and the soaring Gothic choir is one of the cathedral's defining features.
Rather than replacing the earlier building, medieval architects created a dialogue between two architectural worlds.
The result is one of Europe's most fascinating combinations of architectural styles.
Treasures of the Cathedral
Aachen Cathedral preserves one of the richest collections of medieval treasures in Europe.
Among its most famous relics are the so-called Aachen Relics, displayed during the traditional pilgrimage every seven years.
The cathedral treasury also houses magnificent reliquaries, illuminated manuscripts, medieval textiles, and goldsmith work that reflects centuries of imperial patronage.
Together, these objects make Aachen one of Europe's most important centres of medieval religious art.
Its artistic heritage extends far beyond the architecture itself.
A Living Legacy
Today, Aachen Cathedral continues to stand as one of Germany's greatest historic monuments.
In 1978, it became one of the very first sites to be inscribed on the UNESCO World Heritage List, recognising both its architectural significance and its extraordinary role in European history.
Unlike many cathedrals celebrated primarily for their Gothic design, Aachen tells a broader story.
It preserves the legacy of Charlemagne, the rise of the Holy Roman Empire, and the evolution of medieval architecture across more than six centuries.
More than 1,200 years after construction began, Aachen Cathedral remains a remarkable meeting place of Carolingian, Byzantine, and Gothic traditions.
It is not simply one of Europe's oldest cathedrals.
It is one of its most influential.
Sources & Further Reading
Aachen Cathedral - Official Website
UNESCO World Heritage Centre – Aachen Cathedral
Nelson, Janet L. King and Emperor: A New Life of Charlemagne. University of California Press, 2019.
Wilson, Christopher. The Gothic Cathedral: The Architecture of the Great Church 1130–1530. Thames & Hudson, 1990.
Wikimedia Commons – Aachen Cathedral