Some errands are just errands. The Mainz weekly market is not one of them.
You can go for apples and leave with apples. That is allowed. But the Domplätze, three mornings a week, have a way of turning a shopping list into a reason to stay.
It is not a festival. That is the point.
The city runs the Wochenmarkt on Tuesday, Friday and Saturday, from seven until two, across Höfchen, Markt and Liebfrauenplatz. Tourism copy calls it one of the most beautiful markets in Germany. Locals treat it more like a standing appointment.
You bump into someone you did not plan to see. You wait while a neighbour chooses pears. You overhear two languages at the next stall and then a third.
Nothing is programmed except the stalls themselves.
A market is a city practising being a city
A supermarket is efficient. A market is public.
You have to walk. You have to decide in front of other people. You can change your mind about lunch because the cheese looked better than the plan you arrived with.
That slight friction is useful. It puts you in the same weather as everyone else, holding the same paper bag, with no reservation and no ticket.
The social life of Mainz is often just this: being in the same place at the same unremarkable time.
Leave before it becomes a project
You do not need the full Saturday Marktfrühstück, the wine, the programme. A Tuesday with twenty minutes and a list is enough.
Buy what you came for. Talk if talking happens. Walk on.
The cathedral is still there when you leave. So is the rest of the morning.