The story
Frankfurt has been known for its trade fairs for over 800 years. In the Middle Ages, merchants and businessmen met at the "Römer", a medieval building in the heart of the city that served as a market place; from 1909 onwards, they met on the grounds of the Festhalle Frankfurt, to the north of Frankfurt Central Station. The first Frankfurt trade fair to be documented in writing dates back to 11 July 1240, when the Frankfurt Autumn Trade Fair was called into being by Emperor Frederick II, who decreed that merchants travelling to the fair were under his protection. Some ninety years later, on 25 April 1330, the Frankfurt Spring Fair also received its privilege from Emperor Louis IV. And from this time onwards, trade fairs were held in Frankfurt twice a year, in spring and autumn, forming the basic structure for Messe Frankfurt's modern consumer goods fairs.
From Wikipedia’s article on Messe Frankfurt, shared under CC BY-SA 4.0.5