As a child, the Ireland-born Crowley, 54, says he was obsessed with Mary Poppins: ''I saw it four times the first week it opened.'' In the stage version, he tried to ''honor the  film, and be faithful to [P.L. Travers' 1934] book.''
1. The roof drops down for chimney sweeps to perform upon and rises to reveal the kids' room. ''Like a hatbox or Russian nesting dolls, I had a crazy idea that the nursery should sit inside the roof so it appears to float on a cloud.''
2. ''These are almost all genuine items from the Victorian period,'' Crowley says of the junk-shop finds strewn about the set, ''but this isn't the Antiques Roadshow, so nothing is worth much.''
3. A blue and white ceramic vase, which acts as a valuable Banks family heirloom, plays a pivotal role in the show. ''I painted it blue and white because it needed to stand out from all the yellow in the surroundings. Plus, blue is the color of Mary, so it's linked to her.''
4. ''You can't see everything from the audience,'' Crowley concedes, ''but each tiny item, like Mr. Banks' pipe collection or the old family photos, adds up to complete the idea that people actually live here.''