According to one of the plaques in the Hanger 2173 museum, there are 18 km of steel cable that keep the Skyway running.

This is an example of the cables. As another plaque in the museum says (and I did warn you about the floweriness of Italian language, especially when translated to English):
"This is the cable. The hauling cable. We can touch it, feel its resistance, its capacity to move tons, run our fingers over its many threads and grasp them all in our palm. As if we were holding the story of this cable car in our hand: the present that protects and renews the past."

(That's not exactly, word for word, what the translation of the original Italian is, though it's close enough and probably closer than a lot of Google Translate translations.)

Nonetheless, it's a good exhibit and whoever put it on display really knew what they were doing in terms of creating a museum. Here it may seem like it's just a photo of a piece of cable, but when you actually touch it and feel it, you get a sense of how impressive an achievement this cable car system really is. No photograph could ever convey that; it's something that you have to experience. Of course, I did, so for me this is more than a photograph; it's a physical memory.