Platz der Mainzer Republik, 55116 Mainz Saturday, September 13 from 10 a.m. to 6 p.m. Sunday, September 14 from 12 p.m. to 6 p.m. On the weekend of September 13 and 14, 2025, the Mainz Science Market will once again be inviting visitors to discover, try out and marvel - for the first time on the Platz der Mainzer Republik in front of the Rhineland-Palatinate state parliament. Admission is free.