The Matter of Time by Richard Serra occupies a permanent gallery at the Guggenheim Museum Bilbao, where sculpture and architecture operate as a single spatial system. Rather than being viewed from a distance, the massive weathered steel forms are entered, walked through, and experienced over time. Composed of spirals, ellipses, and torqued volumes, the works recalibrate perception through weight, curvature, and scale. Movement becomes the primary medium: space compresses and expands, orientation