Buildings Coloring Book is a nice coloring application for small kids which includes multiple drawings in 3D depicting all kinds of buildings like houses, castles, monuments, apartments, etc. To paint, the kids just need to select the color from the jars by clicking on them and then click on the desired place on the drawing to paint it. The application doesn't include too many colors, but fortunately, kids can create more by combining colors in the palette you find on the right. If you want to clean the brush, you just need to click on the water jar.
If you make a mistake you can use the undo option or you can clear the whole drawing instead and start all over again. Note that the trial will only allow you to paint the first drawings. Fortunately, the program is run in full screen, so the kids cannot have access to your computer. Sadly, you won't be able to print the drawings. The program offers nice graphics and sounds, as well as pleasant music.
In short, if you need a coloring application to keep your kids busy for a while, Buildings Coloring Book can be a nice choice.