On February 24, 1988, two members of the Ulster Defense Regiment were killed by a 200-lb IRA bomb detonated in the center of Belfast, where the Castlecourt Shopping Centre was under construction. A follow-up second bomb, intended for police and soldiers responding to the first blast, failed to go off and was defused by the army. Yesterday morning, 27 years after the event, an annual parade and memorial service effectively closed down access to the commercial center of the city for more than an hour.