Have you ever seen paintings inside a 3-centimeter glass bottle? This is interior painting (内画). There are different schools (派别) of interior painting, and Shandong school is one of them. It’s from Zibo, Shandong and has a history of over 100 years. The artists (艺术家) paint the inside of a bottle, vase or glass ball. The interior painting became a national intangible cultural heritage (国家级非物质文化遗产) in 2014.