Cross sections of a bustling, five-story apartment house at different times of the day appear in huge spreads that require readers to turn the book sideways; ``A Tour of the Old House'' and ``Who's Who in the Old House'' set up the real action. Something is constantly going on in each of the dozens of rooms in the house, in the cellar, and the sewer below it. The illustrations are cartoony but architecturally precise, and in the course of the day, hundreds of events unfold simultaneously: Robbers steal a painting; a scientist's rocket explodes; a kitten is lost; apartments flood; and so on. A running text and captions enable readers to follow various plots, but the best approach to this book is to rummage through the pictures and figure out the flow of events. It's a unique and engaging entertainment, with no sign of Waldo anywhere. (Picture book. 7-11)