Walter, Duke of Athens and tyrant of Florence, also employed Andrea to enlarge the piazza, and to fortify his palace by barring the bottom of all the windows on the first floor, where the hall of the Two Hundred now is, with very strong square iron bars. The same duke also added, opposite S. Piero Scheraggio, the rough stone walls which are beside the palace to augment it, and in the thickness of the wall he made a secret staircase, to mount and descend unperceived. At the bottom face of the wall he made a great door, which now serves for the Customs, and over this he set his arms, the whole after the designs and with the advice of Andrea. Although the arms were defaced by the magistracy of the twelve, who took pains to obliterate every memorial of that duke, yet on the square shield there remained the form of the lion rampant with two tails, as any attentive observer may see. For the same duke Andrea made many towers about the city, and not only began the fine gate of S. Friano, leaving it in its present form, but also made the walls of the portals and all the gates of the city, and the smaller gates for the convenience of the people. And, because the duke purposed to make a fortress on the hill of S. Giorgio, Andrea prepared a model for it, which was never used, as the work was not begun, the duke being driven out in the year 1343. The duke's plan to convert the palace into a strong castle was in great measure effected, for a considerable addition was made to the original building, as may be seen to-day, the circuit comprising the houses of the Filipetri, the tower and houses of the Amidei, and Mancini, and those of the Bellaberti. And because, after this great undertaking was begun, all the materials required for it and for the great walls and barbicans were not ready, he kept back the building of the Ponte Vecchio, which was being hurried forward as a necessary thing, and made use of the dressed stones and timber designed for this without any consideration. Although Taddeo Gaddi was probably not inferior to Andrea Pisano as an architect, the duke would not employ him on these works because he was a Florentine, but made use of Andrea. The same Duke Walter wished to pull down S. Cicilia, in order to obtain a view of the Strada Romana and the Mercato Nuovo from his palace, and would also have destroyed S. Piero Scheraggio for his convenience, but the Pope would not grant him licence. At length, as has been said above, he was driven out by the fury of the people.