This was a popular place to execute Jews, witches, and Heretics. They were tried at the at the other end of the Ile De La Cite at Notre Dame.
They were brought to this remote area to be burned, so they would not pose a fire hazard to the cathedral which was still under construction. If King Philip owed anyone money, they ended up here, thus erasing his debt.
Jacques Demolay, the leader of the Knights Templar, was martyred at this site. The Pont Neuf Bridge is visible.