Some cities are designed for walking through. Mainz is unusually good at stopping.
You notice it in the Altstadt especially. A ledge in the sun. The edge of a fountain. A bench that is not trying to be a destination. Somebody already there, doing very little, which makes it easier for the next person to do the same.
Sitting is a social technology
A table asks you to order. A walk asks you to keep moving. A step or a bench asks almost nothing.
That is useful if you are waiting for someone, if the conversation has not decided what it is yet, or if you simply want to be in the city without consuming it.
Mainz has enough of these leftover surfaces — church steps, square edges, low walls — that you can pause without first solving the problem of where.
The square does not need a programme
Official Mainz is full of events, markets, openings. Those have their place. But a lot of the city's actual social life is quieter than the calendar.
Two people on a step. A student with a coffee. Somebody looking at their phone and then not looking at their phone.
The architecture is old; the use is ordinary. That combination is part of why the centre still works as a place to meet rather than only a place to visit.
A good city gives you somewhere to sit that does not feel like you are in the way.