Trivia: Once the first season with Terri started, Cindy no longer had "Snow" mentioned as her last name for the remainder of the episodes she was in (possibly due to the fact that this was the first season that started without Suzanne Somers completely and the producers wanted to retire the "Snow" surname altogether).
Trivia: Of all 5 roommates (Jack, Janet, Chrissy, Cindy, Terri), the only parent of a roommate never to appear in any episode is Cindy's mother.
Trivia: Jeffrey Tambor, Anne Schedeen, and Jordan Charney have all guest starred in episodes involving Chrissy, Cindy, and Terri. (To avoid confusion, Tambor's episode with Chrissy was technically an episode of "The Ropers" but in recent years played in syndication as "Three's Company").
Answer: I believe you are referring to the artwork of Alphonse Mucha. On the wall next to the front door was "Feather" (which is one half of "Primrose and Feather"). Above the telephone in early episodes was "Zodiac". Also seen through The Apartment was "Spring" and "Autumn".