The guide
One frame, and it is a good one
The square is a long eighteenth-century facade in pale limestone, and in front of it is a shallow sheet of water that reflects the whole thing.
Photographically that is a gift. The reflection doubles the architecture, throws light back up into faces, and produces a symmetrical frame that needs no explanation to anybody looking at it later.
It is also the most photographed spot in the city, and the crowd stands precisely on the reflective surface, which is the whole difficulty.
Timing, which is everything
The mirror runs on a cycle: flooded for a few minutes, then misted, then drained, then repeated. If you arrive in the wrong part of that cycle, the effect is simply not there.
Layered on top of that is the crowd, which builds from mid-morning and does not thin until evening.
So a session that wants this frame is booked either before nine in the morning or late at night. Both work; the second is the more spectacular and the harder to persuade people to agree to.
Winter
The mirror is drained for maintenance for part of every winter. When it is dry, the square is a fine piece of architecture with a large empty forecourt — worth photographing, but not the reason anyone came.
That is worth checking rather than assuming, and it is the single most common disappointment we hear about this place.
What it suits
A few minutes inside a longer couple session rather than an hour in itself — the frame is strong but there is only one of it.
Proposals, late in the evening, when the square empties and a photographer standing thirty metres away with a long lens looks like nothing at all.
And wedding parties, briefly, on the way between the town hall and the reception. For a longer session in the city we move on to the public garden or the old streets, and prices are the same either way on the rate card.