An eruv is a ritual enclosure that Jewish communities construct in their neighborhoods as a way to permit carrying certain objects outside their own homes on Sabbath. An eruv accomplishes this by integrating a number of private and public properties into one larger private domain, thereby avoiding restrictions on carrying objects from the private to the public domain on Sabbath and holidays.
The eruv must be made of walls or doorways at least 1 m high. In public areas where it is impractical to put up walls, doorways are constructed out of wire and posts. For safety reasons, the horizontal wires usually carry one or more marker flags. These flags draw attention to the eruv and add photographic interest.