What did Charlemagne do to restore the old roman empire?

Charlemagne increased the size of the Frankish kingdom to include most of the area of present France, Belgium, the Netherlands, Germany, and Switzerland, and parts of Austria, Italy, and Spain. It was the largest country in Western Europe since the Roman Empire, and much larger than any there today. On December 25, 800, Pope Leo III crowned him Emperor of the Romans, in an effort to reestablish the West Roman Empire. His country did not survive him for long, however, as it was divided among his grandsons. Nevertheless, the countries they began included France and the Holy Roman Empire.

There are links to articles below.