If you’re into staying in odd hotels, the most unusual one in Paris is part of Hôtel Dieu, called Hospitel. Occupying the top floor of Paris’ enormous public hospital, the hotel is adjacent to Notre Dame and features one of the most beautiful hotel lobbies in the world: a sumptuous, verdant courtyard framed by a sprawl of archways.
The location of the Hôtel Dieu was apparently chosen due to its proximity to Notre Dame. (Hôtel in French can mean a large mansion-like building, not necessarily as hotel as we know it.) It was thought that people leaving a house of worship might be more charitable on the way out. Eventually rooms were rented out on the top floor for people visiting patients in the hotel, and thereafter, the hospital opened them up to the public. For those of you that are concerned about noise, I doubt you’ll find anywhere that’s quieter than a hospital.
The rooms are serviceable (think of an Ikea-decorated college dorm room), but hospital-clean without a lot of extraneous decoration.