Aix-la-Chapelle was designed as the tomb of Charlemagne, and here the builders mingled the rotunda of the ceremonial church with the basilica for worship. The workmanship is much more rude than that of S. Vitale, where Greek artists were employed. It is easy to distinguish the parts added by the Comacines, from the classical and Byzantine imported adornments furnished by the spoils of Rome and Ravenna. The Italians were not left entirely free in their designs, but had to conform to a more northern climate and different national taste; the windows were narrowed and elongated, and the pitch of the roof raised to a sharper angle. As Pliny had said to Mustio, his Comacine architect, seven centuries before--"You Magistri always know how to overcome difficulties of position," and Charlemagne's architects, in an equal degree, studied both climate and position. The further we go south or east the roofs have a tendency to flatten, the further we go north they have a tendency to rise into sharper gables. The cause is this, I take it--a climatic one. Where there is much rain or snow, the sloping roof is a necessity; therefore this first indication of pointed architecture, as adaptable to the northern climate, makes Charlemagne's church an interesting link between the Romano-Lombard and Gothic in the north: just as Romano-Lombard stands between the classic and Romanesque in the south. If Ansige suggested these modifications to the Italian builders, he had a wider office in the history of art than he knew; for Aix-la-Chapelle became the root from which the French and German so-called Gothic sprang; improved in the first instance under the hands of the _Franchi-Muratori_, who in the succeeding generations were called to work on churches in both countries. After all, the first step was but a slight one, being more a raising and narrowing of the round arch than the innovation of the pointed one. It might stand better as a first indication of the stilted Norman arch. Of the civil architecture of the Carlovingian era we have very few instances remaining. The Emperor Charlemagne built no especial palace for himself, but used that of Luitprand at Milan, which in Charlemagne's time was known as _Curtis domum imperatoris_. An old chronicler tells us that he fortified Verona. He says--"In the time when King Pepin was still young, the Huns or Avars invaded Italy. When Charlemagne heard of their approach he caused Verona to be fortified, and walls erected all round, with towers and moats; and with _pali fissi_ fortified the city to its very foundations, leaving there his son Pepin." Forty-eight towers rise from these walls, of which eight are very high, the others well raised above the walls. These must have been what the old writer quaintly called _pali fissi_.