Very close to Gare du Nord (and Gare de l'Est is therefore also within walking distance). A relatively quiet place, as it faces inward and not the street front. The building has a tiny Parisian lift. The place is reasonably sized for a one-bedroom apartment in this part of Paris. I had no problem sleeping on the sofa-bed in the lounge room.
Olivia was a hospitable host, and her cat was lovely.