Try to use a themed coloring. For example, a series of coloring books about animals, buildings or machines give children an idea of the objects of the world. Coloring of fairy tales or cartoon characters, are good because they allow the child to "talk" with their favorite characters and express their attitude towards them through colors.
There are rare instances of contour drawings of famous architectural structures and monuments with a variety of parts made in a realistic manner. Such coloring is complex to implement and is designed for adults.