Truly Rome is a world: whatever has possessed greatness in the west -art, religion, history- has left its traces in this city. Pagan antiquity, the origin of Christianity and of Byzantine civilization, the struggles and the transformation of the early middle age, the ecclesiastical supremacy of the thirteenth century, the Renaissance of the fifteenth and sixteenth century -all these epochs had Rome for their centre; they covered it with their works, and they live again in it in a crowd of monuments. How many considerable States present us, in comparison with the reminiscences accumulated here, with nothing but fragments without significance! In such a collection each author has made his choice; one though ought, for once at least, to decide to see all and to study all. Still, even in a special frame, completeness is rare. As day by day and slowly one pursues the pilgrimage of the wonders of Rome, at each step, in the reminiscences of the inhabitants, in the knowledge of the learned men of the country, in forgotten books, and most of all in personal discoveries, one comes upon a series of facts which have not been collected before, and gradually rectifies a multitude of erroneous traditions as to the monuments and works of art. In the midst of the masterpieces that fill the churches and palaces, how many undetected gems! Among the famous ruins, all through the ancient dwellings of the populous quarters and deserted suburbs, how many remarkable footprints that have hitherto been little remarked