Zu Chongzhi (429-501) is one of the greatest ancient Chinese mathematicians. He was taught Mathematics from Liu Hui’s commentary on the Nine Chapters on the Mathematical Art. He was appointed as an officer in the city of Yang-chou and during this time he worked in Arithmetic and Geometry. He gave the rational 355/113 as an approximation of pi in his Zhui shu (“Method of interpolation”) and proved that:
3,1415926 < pi < 3,1415927
Zu also proposed a new calendar (the “Calendar of Great Brightness”) in 462 based on a cycle of 391 years with 144 extra months inserted (=4.836 months).
In the Wikimedia Commons there is this photo of a statue dedicated to him in Tinglin Park in Kunshan.
Google dedicated this doodle five years ago to celebrate his birthday.
Location: Tinglin Park in Kunshan (map)