At daylight on May 18, the citizens were astonished to see a wooden turret or ‘bastion,’ which had been built during the night.[338] The turret had been constructed with the same secrecy and celerity that Mahomet invariably adopted in the execution of his plans. Barbaro declares that all the Christians in the city could not have made it under a month. It was a huge structure. It was only in the morning, when they saw it complete in a place where no preparations had been observed on the previous evening, that they realised what had been done. This ancient form of the ‘Taker of Cities’ was stationed near the Romanus Gate. It consisted of a strong framework of long beams so high as to overlook the Outer Wall.[339] It had been partly filled with earth, faced with a threefold covering of camels’ or bullocks’ hides, and was built on wheels or rollers. Steps led to its upper platform. These and the road which led to the camp, which was sufficiently distant to be out of range, were also covered for protection. Scaling-ladders could be raised and thrown from the summit of the turret to that of the wall. If the huge machine was, as Barbaro states, within ten paces of the wall, it must have been built in the foss itself. It dominated the outer barbican or enclosure and would have allowed the enemy under cover of its protection to fill the ditch from three openings which were in the side presented to the walls and to undermine them in safety. The latter probably was the principal object for which it was intended. It would also have enabled the Turks to prevent the besieged from repairing the damages to the Outer Wall caused by the cannon. For this reason we can understand the statement of Barbaro, that while it gave increased hope to the Turks, it filled the besieged with alarm. It was built, according to Tetaldi, opposite the place defended by Justinian.[340] Its dangerous character was soon shown. The cannon having destroyed one of the towers near the Romanus Gate, the turret was moved and stood overhanging the ditch. A fierce fight took place between the Turks inside it and the Greeks and Italians under Justiniani. The Turks flung earth, wood, and all kinds of material available into the foss, employing mainly the stone from the ruined tower, so as to form a level pathway across. The besieged fought hard from daylight till after sunset to prevent the Turks from making use of the turret, and the emperor and Justiniani assisted all the night at the repair of the tower.