 The blast furnace is the vertical structure with the blank arches at the lowest part of the site.The furnace within was supplied with raw materials (iron ore, coke, and limestone) by tipping them in through a charging port at the top, accessed from the bridgeloft.The loading ramp, which spans the Ashby Canal, allowed the raw materials to be raised into the bridgeloft, which comprises the top floor of the bridgehouse, the large building with the pitched roof behind the furnace.