noon before
On the second floor , they found a museum ; many of the exhibits remained , tantalizingly half-visible in grimed glass cases . There had been administrative offices there , too . The doors of most of them were closed , and they did not waste time trying to force them , but those that were open had been turned into living quarters . They made notes , and rough floor plans , to guide them in future more thorough examination ; it was almost noon before they had worked their way back to the seventh floor . Selim von Ohlmhorst was in a room on the north side of the building , sketching the position of things before examining them and collecting them for removal . He had the floor checkerboarded with a grid of chalked lines , each numbered . `` We have everything on this floor photographed , '' he said .