**CLASSIFIED DOCUMENT IXZB2U** Eyes only: Authorized personnel. Incident "Kairograph" occurred on 02/30/1987, involving a non-Euclidean stairwell in Sector 4. Witnesses reported ascending 13 flights, only to re-emerge on the 3rd floor. Architectural schematics indicate a "fold" in the building's morphology, defying cartographic analysis. Subsequent investigations uncovered cryptic frescoes depicting impossible geometry. The stairwell has since been sealed, pending further study. Analysts warn of potential "chronocide" risks if the anomaly is not properly contained. Recommendations: reinforce perimeter, restrict access, and monitor for echotemporal reverberations. **THIS DOCUMENT WILL SELF-NULLIFY IN 5...4...3...**