where am I.?

I pushed past the soft valley of the sheets and stepped onto a solid, polished plane. My plastic feet clicked against the dark wood. Ahead stood a tall, rectangular stack of thick paper volumes. Their crisp, straight spines rose at perfect right angles. I halted, pausing two paces away. Slowly, I tapped one foot against the bottom spine. Solid. No sudden movement. I squared my torso along the dark seam where two books met, letting the clean vertical line guide my posture, and settled into the narrow shadow between them.[;