As four adults, we spent one night in Chris' Airbnb on 17 August at Drummond Street in Edinburgh Old Town. The apartment was clean, spacious, and in a great position to enjoy the Fringe.
It was a nice touch for Chris to provide us with the basics (tea, coffee, milk etc.) plus a bottle of champagne as a welcome present.
The place is unique in as much it is clearly a listed building (an ex-boys' boarding school, I think, with multiple apartments) and is probably also home to students and young professionals. All in all, it's great place from where to explore Edinburgh.