Niccola had, among others, a son called Giovanni, who, because he ever followed his father and applied himself under his teaching to sculpture and to architecture, in a few years became not only equal to his father but in some ways superior; wherefore Niccola, being now old, retired to Pisa, and living there quietly left the management of everything to his son. Pope Urban IV having died at that time in Perugia, a summons was sent to Giovanni, who, having gone there, made a tomb of marble for that Pontiff, which, together with that of Pope Martin IV, was afterwards thrown to the ground when the people of Perugia enlarged their Vescovado, in a manner that there are seen only a few relics of it scattered throughout the church. And the people of Perugia, at the same time, having brought a very great body of water through leaden pipes from the hill of Pacciano, two miles distant from the city, by means of the genius and industry of a friar of the Silvestrines, it was given to Giovanni Pisano to make all the ornaments of the fountain, both in bronze and in marble; wherefore he put his hand thereto and made three tiers of basins, two of marble and one of bronze. The first is placed above twelve rows of steps, each with twelve sides; the other on some columns that stand on the lowest level of the first basin--that is, in the middle; and the third, which is of bronze, rests on three figures, and has in the middle certain griffins, also of bronze, that pour water on every side; and because it appeared to Giovanni that he had done very well in this work, he put on it his name. About the year 1560, the arches and the conduits of this fountain (which cost 160,000 ducats of gold) having become in great part spoilt and ruined, Vincenzio Danti, a sculptor of Perugia, without rebuilding the arches, which would have been a thing of the greatest cost, very ingeniously reconducted the water to the fountain in the way that it was before, with no small credit to himself.