NEW : ` ` He and our city will forever be linked , '' the mayor says . Mike Rawlings says ` ` hope and tragedy collided '' in Dallas 50 years ago . Moment of silence , bells , a moment Demonstrators gathered at Dealey Plaza on Thursday , and many chanted : `` No more lies . 50 years ago Kennedy was assassinated . Stone laid in Dallas ; House prayer invokes Kennedy 's memory .
NEW : ` ` He and our city will forever be linked , '' the mayor says . Mike Rawlings says ` ` hope and tragedy collided '' in Dallas 50 years ago . Moment of silence , bells , a moment 50 years ago Kennedy was assassinated . Stone laid in Dallas ; House prayer invokes Kennedy 's memory .