Will a worm farm in the city attract rats?

Image by davnull
red worms’ farm on april 24, 2008 at the OK mediendeck for the crossing europe film festival in linz, austria. for more go to davnull.webhop.org

Question by AnitraWeb: Will a worm farm in the city attract rats?
Some volunteers built a small raised-bed garden for our low-income apartment building. The soil looks like pretty good sandy loam, at least a foot deep, but short on nutrients and with NO organic matter whatsoever, and NO worms (or any other living beasties, as far as I can tell.) We’ll buy some organic additives before we plant, but I would like to get some worms in as soon as possible. I’d like to set up a worm farm. but we already have trouble with rats, and we don’t want more!

What is the absolutely cheapest set-up for a worm bin, that will be secure from rats? Do you have a persuasive argument for keeping it inside, that would work on staff worried about hygiene and odor?

Can you help? Leave your own answer in the comments!