One of my favourite squares in Paris is Place des Vosges in the Marais district. It oozes of its old 17th century charm with its arcades, art galleries, its garden with its fountain and not least its beautiful buildings.
First time I was there, all trees were in full bloom in Spring giveng the charming square a lovely soft light. This time was in the midst of winter with all trees bare waiting for sunshine. Trees without leaves give on the other hand a lovely random pattern towards the sky, in contrast to the benches and fountains placed in straight lines, as well of course the arcades surrounding the full square.
Do go and visit Place des Vosges next you are in Paris.