In the middle of the Marais, across the Museum Picasso. It's a perfect place if you want to visit Paris, as all the touristic sites are nearby (walking or with public transports).
Near subway stations: Saint Sebastien Froissard - line 8, Saint Paul - line 1, Rambuteau - line 4.
3rd floor with no elevator.
In the main room, a sofa bed for two, a dining place, an American kitchen.
In the bathroom - sink and bathtuv.