By the side of the "Beautiful Doorway," leading into the cloisters of the cathedral at Mainz, stands, worked into the wall, a fragment of the tomb of Fastrada, the fourth wife of the mighty monarch Charlemagne according to some authorities, the third according to others. Fastrada figures in the following tradition related by the author of the Rhyming Chronicle.
When the Kaiser, Karl, abode at Zurich, he dwelt in a house called "The Hole," in front of which he caused a pillar to be erected with a bell on the top of it, to the end that whoever demanded justice should have the means of announcing himself. One day, as he sat at dinner in his house, he heard the bell ring, and sent out his servants to bring the claimant before him; but they could find no one. A second and a third time the bell rang, but no human being was still to be seen. At length the Kaiser himself went forth, and he found a large serpent, which had twined itself round the shaft of the pillar, and was then in the very act of pulling the bell rope.
"This is God's will," said the monarch. "Let the brute be brought before me. I may deny justice to none of God's creatures—man or beast."
The serpent was accordingly ushered into the imperial presence; and the Kaiser spoke to it as he would to one of his own kind, gravely asking what it required. The reptile made a most courteous reverence to Charlemagne, and signed in its dumb way for him to follow. He did so accordingly, accompanied by his court; and the creature led them on to the water's edge, to the shores of the lake, where it had its nest. Arrived there, the Kaiser soon saw the cause of the serpent's seeking him, for its nest, which was full of eggs, was occupied by a hideous toad of monstrous proportions.
"Let the toad be flung into the fire," said the monarch solemnly, "and let the serpent have possession of its nest restored to it."
This sentence was carried at once into execution. The toad was burnt, and the serpent placed in possession. Charlemagne and his court then returned to the palace.