Democratic Convention protesters declare a free speech zone of their own: The streets around the Democratic National Convention site resembled an armed camp on Sunday - helicopters overhead, bomb-sniffing dogs and their handlers, police officers and soldiers lining the intersections, many kinds of barriers, and an officially designated "Free Speech Zone" sealed off with cyclone fencing and razor wire. It looked like an empty cage. The designated demonstration area, a dank place under abandoned elevated tracks, failed its first test on Sunday when what will probably be the largest demonstration of the convention period simply walked right by it...Indeed, the Free Speech Zone is rapidly becoming the hottest local issue of the convention, with most of the protest groups vowing to boycott it. The only protesters to embrace it were members of a pro-Palestinian group that says the cyclone fencing and barbed wire provide an ideal visual backdrop to their message of opposition to the Israeli occupation of the West Bank. ...Sunday's demonstrators, mostly antiwar, numbering about 3,000 by police estimate, marched for about two hours in a big circle from the Boston Common over the top of Beacon Hill past the FleetCenter, the convention site, proceeding back past Government Center to the common, without serious incident. There was a brief scuffle with one of many anti-abortion protesters, who were also out in force. ...After the American Civil Liberties Union and the National Lawyers Guild filed suit against the zone, Judge Douglas P. Woodlock of Federal District Court toured the site last week and said that while he intitially doubted the lawyers' claim that the site resembled "an internment camp," he concluded that the comparison was "an understatement." "One cannot concieve of other elements put in place to create a space that's more of an affront to the idea of free expression than the designated demonstration zone," he said in a ruling on Thursday. Nevertheless, Judge Woodcock said, there was no alternative. He told the lawyers: "There really isn't any other place. You're stuck under the tracks."