Figure 2. The 2D Peano curve is constructed using an iterative procedure. In this procedure, each line segment is folded into eight segments, which preserve the start- and end-point while sweeping out an adjacent 2D area. In the mathematical limit - after the procedure is repeated infinitely many times - the curve touches every point inside the square. This raises the question of whether the curve, first constructed by Giuseppe Peano in 1890 (Peano, 1890), is one- or two-dimensional, or whether this notion of dimensionality is even meaningful. The original report introducing space-filling curves by Peano introduces the concept using mathematical language, but does not include a visualization of the curve. It is challenging to make this seminal concept intelligible and intuitive to the mind and senses. Motivated by Peano’s study, Hilbert’s 1891 contribution included a new, similar curve, complete with a diagram to assist the reader’s intuition.