Way back when, my father-in-law bought me a Little Giant folding ladder that, despite its name, ain't so little. Still, I didn't think anyone could create a ladder smaller than that, so I was plesantly surprised to learn about the Corner Ladder by design studio Company & Company:
Made for small domestic spaces, barcelona-based design studio company & company have sent us images of 'corner ladder'. The redeveloped useful tool is made to fold not only flat, but also compresses horizontally into a single pole. The hinges and dowels make it easy to open and close while the wooden device maintains its structural stability. To make space for the folded rungs, the rails have indented space, allowing for the frame to unite into a single bar.
Given the price, I would separately buy a step ladder, a 16 ft extension ladder and a six foot folding ladder.
As for the ladder from this post, as soon as it is on the market, I am buying one.