Mayor Michael Bloomberg was sworn in for another four years on Sunday and launched his second term portraying the city at a critical crossroads, with the promise of "finishing our unfinished work." Bloomberg took the oath at an afternoon City Hall ceremony. His first address of 2006 touched on the progress he believes he has made, and tried to set an aggressive tone for the next four years. The former CEO and then-political novice took his first oath of office on New Year's Day in 2002, as rescue workers still searched for victims' remains amid the World Trade Center rubble. The economy was in tatters, and he warned of tough times ahead. This year, in his second inaugural address, the Republican mayor recalled that day and the tragic point in the city's history, saying those wounds "may never fully heal." "This is not the time to relax our vigilance," Bloomberg warned Sunday, adding that his administration must "live within its means." Echoing his 2002 address, the mayor - a lifelong Democrat who changed parties just before his 2001 race - promised again to govern "without partisanship or prejudice."