We checked in at this location without a hitch...the door was open and the key was on the ledge by the door. The apartment is dated and apartment was a bit musty smelling. The kitchen and living room area are very dark - little to no natural light gets in but the upstairs bedroom is nice and bright. A bottle of wine was left on the counter - nice touch for people who imbibe. Kitchen utensils and implements were sparse.
The issue came when we were shutting down for the night. We turned off the lights around 10:45 and within 5-10 minutes we heard a bang like someone was on the stairs. When I sat up there was a man standing in our bedroom. He had entered through a door in the bedroom opposite the stairs (not the main door of the unit) that we thought was a locked closet. We packed up and left within the hour.
The owner told us it was her boyfriend who had entered the apartment in error. She said we hadn't let her know we were there and he was checking on the place. Regardless of whether we had notified her or not, nobody should have unauthorized access to the space you are staying in. We had no control over the point of access and in future, if we ever get the courage up to rent an airbnb again, we will make sure to ask any owners whether they can access the accommodations when we are there.
Still working with Airbnb to get a refund a week later...as of right now they are "investigating".