The arbor is the space between 123 Sesame Street and Hooper's Store that houses the carriage house. The area — which has also been referred to as a courtyard, the play yard, or simply the yard — has gone through many changes over the years.
During the first season, when the street was straight, this area was confined simply by a tall fence with a palm tree painted on it. The space was occupied by some lawn chairs where stories would sometimes be read.
When the show went into its second season, the street was curved, expanding the area. At first, the arbor included a tall fence next to Hooper's Store separating the area from a simple backdrop of apartment buildings in the distance, and a tower with the alphabet painted on it.
The arbor can be looked over from Bob's apartment window above Hooper's Store and Maria's window above 123 Sesame Street. The space is often occupied by tables and chairs where customers of Hooper's Store can enjoy a treat or play a game with a friend.
In the late 1980s, the background was gradually updated. By 1989, more distant buildings were added, and the alphabet tower was converted to a set structure that stood behind the garage (and was later repainted gray when the set was cleaned up and brightened in 1993).
The fence was shortened in 1998, and the backdrop was replaced with a small two-story apartment building. The alphabet tower made way for another apartment building, and a small community garden was added in between the garage and 123.