The earliest records of a procession in Halle, which would more than likely have been a prayer procession, date back to 1335. Even though the format of the Marian procession has changed over the course of time, Marian devotion has always taken stage. These days, the procession consists of two main parts. The first part tells the history of Halle, with a particular focus on the history of processions and pilgrimages in the city. The second part is devoted to Our Lady.
Further information: http://www.mariaprocessie.be/