Meanwhile Niccola was staying at Florence, obtaining practice not only in sculpture but also in architecture by means of the works which were in progress throughout Italy, but especially in Tuscany, with some amount of good design. Thus he contributed not a little to the abbey of Settimo, left unfinished by the executors of Count Hugh of Brandenburg, as the other six had been, as we have noticed above. For although an inscription on the campanile of the abbey reads "_Gugliel me fecit_" yet it is clear from the style of the work that it was carried out under the control of Niccola. At the same time he was building the old palace of the _anziani_ at Pisa. This building has been dismantled at the present time by Duke Casino, who has used a part of the old edifice for the erection of the magnificent palace and convent of the new order of the knights of St Stephen, after the designs of Giorgio Vasari, Aretine painter and architect, who has done his best with the old walls, to adapt them to the modern style. Niccola designed many other palaces and churches at Pisa, and he was the first, after the loss of good methods of construction, who introduced the founding of buildings at Pisa upon pillars connected by arches, first driving piles in under the pillars. This method renders the building absolutely secure, as is shown by experience, whereas without the piles, the foundations are liable to give way, causing the walls to fall down. The church of S. Michele in Borgo of the monks of Gamaldoli was also built after his plans. But the most beautiful, ingenious and fanciful piece of architecture that Niccola ever constructed was the campanile of S. Niccola at Pisa, where the friars of St Augustine are. Outside it is octagonal, but the interior is round with a winding staircase rising to the top leaving the middle space void like a well, while on every fourth step there are columns with lame arches, which follow the curve of the building. The spring of the vaulting rests upon these arches, and the ascent is of such sort that anyone on the ground always sees those who are going up, those who are at the top see those who are on the ground, while those who are in the middle see both those who are above and those below. This curious invention was afterwards adopted by Bramante in a better style with more balanced measurements and richer ornamentation, for Pope Julius II. in the Belvedere at Rome, and by Antonio da Sangallo for Pope Clement VII. in the well at Orvieto, as will be said when the time comes.