In our fifth animation in the máthēma series, we visualize the square root of minus one. The existence of imaginary numbers was first theorized by the philosopher René Descartes, but it took a century until Leonhard Euler was able to solve equations with them, thanks to his invention of the notation "i" to express the imaginary unit √(−1). The animation explores the concept of imaginary numbers through a matrix of fractal volumes, resembling a city or a circuit board. The volumes are classic geometric shapes, but the math behind the distribution, scaling, and repetition, is based on fractals derived from the equation i^2 = -1.