I was wandering through the Plaka, on the hunt for some last-minute knickknacks and on my way from the Agora to a new/old cafe I wanted to try (Kimolia Art Cafe, in case you're wondering, and yes, it's lovely) and I saw a sign for the "Oldest House in Athens." I had to check it out - and I discovered the Benizelou Mansion, aka the House of St. Philothei. It's located at 96 Adrianou Street, and I had a dim recollection of seeing the house from the backside on a walking tour of Athens last summer. It apparently underwent years of renovation and has just this February opened to the public.
The "museum" is impressive - open, light, and accessible. There are two floors, and interpretive screens (not all of them working yet) in several rooms provide insights into life in Ottoman Athens. I couldn't see the entire house, since it was almost closing time and they were shutting it down room by room, but what I did see was a great way of experiencing the home of a noble family of the mid-18th century. Most impactful was the inclusion of not only signage in Greek and English, but in Braille as well (see the images in the slideshow).
Best of all, entrance is free, but note the limited hours of the museum: right now, it is only open on Wednesdays and Thursdays from 10 am to 1 pm and Sundays from 11 am to 4 pm. I couldn't find much info about the Benizelou Mansion online, so hopefully this will serve as a short guide for travelers in Athens wanting to learn more about this fascinating time period of the city, to which the opening of the Benizelou Mansion is a welcome addition.