Stupas originated in India around 4th century BCE and later the idea spread around Asia . In China it was then combined with the Chinese Watchtowers, and then as such it spread (under the name Pagoda) to other countries, such as Japan.
The answer is artistic. This is because artistry is in its original form, just like alternative music. It's not going by the crowd and only being influenced by how you feel. Hence, art.
