Not a hermitage but a prison cell.
It's in Assisi and, according to the local story, this is the place where Francis spent some time after his father had him arrested.
What? Dissension within a saint's family? It's a long tradition apparently. There are a number of virgin-martyrs on the Saints List because they didn't want to marry who Papa proposed. All of those were women, strangely enough. Can't think of a single man whose Daddy tossed him in the clink for refusing to marry.
So why did Francis spend time in the Assisi jail? In his efforts to rebuild the crumbling church of San Damiano, seems he sold off some cloth owned by his merchant father and then gave the money to the caretaker-priest. Collecting and refurbishing stones wasn't enough to do the job, so Francis went where the money was.
It got worse. Eventually, his father was so embarrassed by Francis and his actions that he hauled him before the local bishop and told the bishop to make his errant son conform and obey. In one of the great dramatic Lives of the Saints scenes, Francis told the bishop, "Look, I'm clearly upsetting my father. So I'm giving him back his clothes and his name and from now on, I'll only call God 'Father.'" The bishop had the good sense to order someone to cover him up.
There's no record that Francis and his father, Pietro, ever reconciled.
Assisi is a small town. Everyone knew the business man, Pietro. And everyone knew his wildly extravagant, party-throwing son. What Francis did is much like the boy-who-became-Prodigal, who demanded his part of the inheritance although his father was still alive: "I don't need you, old man." What a deep wound to the heart and spirit. Can you imagine the talk around town? The sides that people would have chosen?
How much business did Pietro lose? How many other parents commiserated with him when their own children wanted to follow Francis' example and leave behind the middle-class life?
How many sermons were preached about honoring one's parents? Being respectful? Not causing shame?
Did either man ever regret that day in front of the bishop?