Hotel Particulier MontmartreFirst you have to ring a discreet door at number 23 so that one opens and you can access the passage that leads you to another door where you still have to ring to get in and discover a magnificently mansion has become a hotel. The reception will show you how to access the bar in the basement overlooking a beautiful little garden. The ideal place is you want to surprise a friend there. They also have a restaurant but did not try it yet and they organize sunday brunches in the front garden during summer: http://hotel-particulier-montmartre.com/