An eruv (עירוב) is a virtual enclosure that defines a larger space as “home”, allowing ultra orthodox Jews to carry on activities otherwise forbidden on Shabbat. The fact is that on Saturday, according to the Talmud, observant Jews are not allowed to carry anything, once they get out of home! Anything, means literally anything, including keys, medicines, or even babies! And there are also many other activities that are forbidden!
To solve the problem
So, to solve the problem on how to be allowed to get out of home on Shabbat, the concept of eruv was introduced. That is, a portion of the city, usually a quarter or a neighborhood, is enclosed in a virtual space. The enclosure is defined by existing walls, bridges, train lines. Where these structures are not present, a rope or a wire are used to demarcate the eruv. In modern Jewish the term eruv often refers to the rope itself that creates this symbolic area.
If you look carefully at the picture above, you will see a white thin thread: from the upper left side of this picture, connecting to the pole and continuing down to the lower right. I wonder how many people walk every day down 6th Avenue in Manhattan, without ever noticing the eruv. Often the most interesting things are in front of our eyes, but we just do not notice them.
On the side: the map of Manhattan’s eruv. In case you decide to convert. Or just to take some photos. (In this last case, please contact me, I’d love to get a copy of the photos!)
On my photo blog dedicated to the city of Antwerp, in Belgium, I have posted a picture of the local eruv: http://antwerphoto.wordpress.com/2013/01/13/antwerps-eruv/
(And it seems I am the only person in the world to collect photos of eruvin.)