Roebling's bridge was supported by two limestone towers on each side of the gorge. These Egyptian-style towers stood tall on the American shore and tall on the Canadian shore. With their foundations in the earth, the limestone structures could support up to 12 million pounds (5.4 million kg). Four thick main cables held up the bridge; two cables ran through iron saddles at the top of each tower. Each cable comprised 3,059 wires that were spun with Roebling's patented technique used in his Allegheny Suspension Aqueduct. The ends of each cable were secured to cast-iron plates sunk deep in the bedrock. Support lines hung down from iron clamps that encircled the main cables, and held up the decks. Deep trusses—never before seen on a large suspension bridge—lined the sides of the bridge, and joined the two decks so that the structure looked like a cage. The trussed sides and the upper and lower decks, which spanned , formed a "hollow straight beam," reinforcing the rigidity of the bridge.