If you're an adult colorer looking for some advanced templates to challenge you, then break out the colored pencils because ...

Adult coloring books have reached a serious peak. It's almost normal now to pop in a coffee shop and see a grown woman with her colored pencils Van Gogh-ing an intricately drawn butterfly.

Johanna Basford's intricate hand-drawn coloring books for adults have sold nearly 1.5 million copies worldwide. Courtesy of Johanna Basford/Laurence King Adulthood seems to be having a regressive ...