US President-elect Barack Obama has attended a ceremony at Arlington National cemetery on his first official engagement since arriving in Washington for his inauguration on Tuesday.It was his first stop at the end of a three-day 220 kilometre train journey from Philadelphia, designed to emulate a similar trip taken by Abraham Lincoln before he took office in 1861. An unprecedented security operation greeted the man destined to become the 44th US President before he laid a wreath at the Tomb of the Uknown Soldier. He is scheduled to attend a concert on the National Mall, launching a four-day inauguration festival. U2, Beyonce and Bruce Spingsteen are to perform, with Obama welcoming a crowd expected to swell to a half a million. On Tuesday. hundreds of thousands of people are expected to pack the inaugural parade route along Pennsylvania Avenue between the White House and Capitol Hill. As many as a million people will be packed into the National Mall to watch the event. Nearly 240,000 people are due to attend the swearing-in ceremony. Despite the freezing weather, Obama fever appears to be gripping the entire population. One bystander said: “It feels like we’ve realised a dream. But I feel like it belongs to every single American that’s worked hard in this country. So we feel very, very patriotic, as always, right?” she asked her young daughter. “And very cold,” came the shivering reply. During the course of his journey to the White House, Obama has warned Americans of the vast challenges ahead, taking office as he does, amid the deepest economic crisis in generations with wars in Iraq and Afghanistan.