Rome was too large for the Goths to completely encircle. So they set up seven camps, overlooking the main gates and access routes to the city, in order to starve it out. Six of them were east of the river, and one on the western side, on the "Campus Neronis", near the Vatican. This left the southern side of the city open. The Goths then proceeded to block the aqueducts that were supplying the city with its water, necessary both for drinking and for operating the gristmills. The mills were those situated on the Janiculum, and provided most of the bread for the city. Although Belisarius was able to counter the latter problem by building floating mills on the stream of the Tiber, the hardships for the citizenry grew daily. Perceiving this discontent, Vitiges tried to achieve the surrender of the city by promising the Roman army free passage, but Belisarius refused the offer, telling his foe: