A conspiracy, which Leo III. only escaped by climbing the walls of Rome and by taking refuge with the Duke of Spoleto, who had marched to his succour, gave him an opportunity for going to see Charlemagne at Paderborn, who promised to come himself into Italy to confound the enemies of the holy father; in the meanwhile he dispatched commissioners to Rome, who reinstated the pope in his pontifical city (November 30, 799). Charlemagne came to Rome in the following year, when, convoking an assembly of the people, he declared the object of his visit and summoned the accusers of the pope to appear before his tribunal. As they did not dare to put in an appearance, he declared that the holy father should be allowed to justify himself on oath. Then in the great cathedral of St. Peter, in the presence of a vast concourse of people, Leo, with his hand upon the books of the Evangelists, cried out, “I know nothing of the crimes with which the Romans have charged me.” His declaration was received with shouts of applause that rung through, the vaults of the sacred edifice. Charlemagne, who had returned to St. Peter’s on Christmas Day, for the service, knelt before the altar. The pope, upstanding before him, placed upon his forehead a golden crown studded with jewels and proclaimed him emperor, thus giving him a real supremacy over all the Christian princes and people of the West. (Figs. 208 and 209.) [Illustration: Fig. 209.--The Coronation of an Emperor by the Pope, the Sovereign being represented by Maximilian I.--From “Des Sainctes Ceremonies,” a Manuscript of the Sixteenth Century, in M. Ruggieri’s Collection.] The popes who were contemporary with the successors of Charlemagne, though not of special note, governed the Church with wise moderation; and as they were all patrons of the Fine Arts, Rome is indebted to them for some of her chief embellishments. Leo IV., in 847, was compelled to make Rome secure from an attack by the Saracens, who were always making incursions up to its very walls. For this purpose he constructed around the church of St. Peter a regular town--the Leonine city--which he fortified with high towers. He also fortified the places near Rome, and founded a new city, called Leopolis, which he surrounded with ramparts. Rome thus being out of danger, he imitated the example of his predecessors by ornamenting the churches, to which he gave paintings and other works of art of the value of 5,971 silver marks. The fabulous story of Pope Joan--who was said to have been elected pope, and to have concealed her sex, though she was shortly after expelled, after some great scandal--is placed by historians between Leo IV. and Benedict III.; but the falsity of the story is manifest, for there was no interregnum between the death of Leo, upon July 17th, 855, and the election of Benedict.