On Sunday afternoon, Aachen is a quietly typical German bourgeois town, with a brass band playing in the Cathedral square and teenagers wearing t-shirts emblazoned with legends like NEW YORK FUCKING CITY. It has hot springs, which, along with its central position between France and Germany, may have been what attracted Charlemagne, Karl der Groesse, the man who invented Europe. The Romans were Europeans, but their empire was of the Mediterranean, with Britain and the Danube bolted on almost as afterthoughts; Antioch and Alexandria were more crucial to them than London or Lyon. Charlemagne was the first to create a Europe that spanned France and Germany, with parts of Italy, Spain, even Poland thrown in.

In Rome in 800, the Pope crowned Charlemagne Holy Roman Emperor – successor to Caesar Augustus, and direct counterpart, if not rival claimant, to the Eastern Roman Emperor in Constantinople. That is emphasized here in his capital by the gorgeous Byzantine mosaics on the walls and ceilings of what was his church – even if they were put in place over a thousand years later:

The shape of the church is an octagon – a Byzantine idea – as opposed to the cruciform floor plan of western churches. In it the Holy Roman Emperors were crowned, right up to the 16th century. In the treasury stands a thousand-year-old piece of their kit, the Cross of Lothar:

Like its countpart pieces of imperial regalia in the Vienna Schatzkammer, this fantastically rich, jewel-encrusted object has none of the finesse of the artifacts of later ages; the bottom of the cross is slightly off the perfect horizontal one would expect, and at its centre, instead of the standard Christian image of crucifixion, it bears, from the time of Christ, the most powerful image of worldly authority in European history: a cameo of Caesar Augustus, wreathed as emperor and holding aloft an eagle.

Barbarossa, the Holy Roman Emperor after whom Hitler’s insanely disastrous invasion of the Soviet Union was named, set Charlemagne’s supposed remains here in a raised golden casket in the choir (you can see it at extreme bottom left of this photo):

He also contributed a large golden circlet for a chandelier:

The Holy Roman Empire ultimately became a German kingdom, and France went its separate way; it was not until the grandiose pride of Bonaparte, the horrors of Hitler, and finally, consensually and in peace, the European Union, that they were to be put together again. No more crucifixions for Europe, we hope; instead, look! no hands: