You Can't Take a Balloon into the Metropolitan Museum - Jacqueline Preiss Weitzman, Robin Preiss Glasser
This is a wonderfully detailed, beautifully executed wordless book. The 'authors' have created a clever, funny and entertaining storyline that incorporates 'real' art with 'real' life. And it's just plain fun. The illustrations remind me a lot of Hilary Knight (Eloise). Highly recommended!