Things to notice
This is the impossible house! The porch, as seen from the inside, is perfectly recreated to match the exterior, but the rest of the matching is nonexistent. Like in Starsky’s Tree House, the living room/kitchen areas of this house are joined at an angle, but I removed that angle to make it match the rectangular house. And tweaked a few other walls, too.
The bathroom has no sign of a toilet. Then again, I notice I assumed that wall to be there right next to the wash basin. It might be a huge bathroom!
This house has a lot of seating for a single guy’s apartment: two couches and lots of chairs. I notice I put in one chair twice: the lone one under the arch is a double. But then the television (the little rectangle next to the fireplace and the peacock chair) is actually on a chair, too, so there still is a full dozen chairs. 😛
The same set is used at least in Hostages, Murder at Sea and The Las Vegas Strangler, which both take place before Starsky moves to the Tree House. I have no idea if the set (mostly recognisable for its kitchen) makes an appearance even later in the show (or other shows), or if the set was completely remodeled to serve as the Tree House. The little angle there suggests that it might have been the same set, or then that angle thing was just something they commonly did to get better views of an apartment set.