The United States will Friday mark the 50th anniversary of the assassination of President John F. Kennedy, a dark turning point in the nation's history and a day many still remember vividly. Church bells will toll. Flags will be lowered. Wreaths will be laid. Children will sing. And in cities and towns across the country, people will reflect upon the words of a charismatic president whose soaring rhetoric continues to inspire. In a proclamation ordering flags be lowered to half-mast, President Barack Obama Thursday recalled Kennedy's leadership in the Cuban Missile Crisis, his Cold War "Ich bin ein Berliner" speech in divided Berlin, and efforts to advance the rights of African Americans and women in the United States. "Today and in the decades to come, let us carry his legacy forward," Obama wrote. "Let us face today's tests by beckoning the spirit he embodied -- that fearless, resilient, uniquely American character that has always driven our Nation to defy the odds, write our own destiny, and make the world anew." Kennedy's voice still echoes through history to so many Americans. “Ask not what your country can do for you; ask what you can do for your country," he urged Americans at his inaugural address on January 20, 1961. Cut down in his first term at the age of 46 as he was driven through Dallas, Texas in an open-top limousine on November 22, 1963, Kennedy's unfulfilled promise has become a symbol of the lost nobility of politics. 'The power to change this country is ours' He was a president who enlisted the nation in lofty goals -- like putting a man on the Moon -- "not because they are easy, but because they are hard." And he declared that we "will be remembered not for our victories or defeats in battle or in politics, but for our contribution to the human spirit.” Obama hailed Kennedy's legacy at a ceremony Wednesday for recipients of the Presidential Medal of Freedom, which the slain Democrat established months before his death. 'The power to change this country is ours' "Fifty years later, John F. Kennedy stands for posterity as he did in life -- young, bold and daring," said Obama, who was two years old when Kennedy was killed. The anniversary has sparked a prolonged period of national and media reflection on the unfinished tenure of the nation's 35th president, his tragedy-stricken family and the evocative period in the early 1960s when his political star illuminated the world. He was the fourth US president to be killed in office, but the first whose death was caught on film. The shocking crime – and the image of blood splattered on the pink Chanel suit of his glamorous wife Jackie – stunned the world and traumatized the nation. Many refuse to believe the killing could be the act of a single man: troubled Marine Corps veteran turned Soviet defector Lee Harvey Oswald, 26, who pointed a rifle out a sixth floor window of the Texas Book Depository and fired on the presidential motorcade. Conspiracy theories continue to captivate doubters and aid an allied industry of books, films and television specials. The most prominent ceremonies marking his passing will be held in the places with the strongest Kennedy claims: his birthplace of Massachusetts, the Washington of his White House victory and Dallas, where he died. A moment of silence will fill Dealey Plaza and its infamous grassy knoll as Dallas marks the moment the shots rang out at 12:30 pm (1830 GMT) before celebrating Kennedy’s legacy with music, prayer and speeches. Elsewhere in the city, the Texas Theater will be screening the film that Oswald was watching when he was arrested -- War is Hell -- while the Frontiers of Flight museum will display a replica of the airplane on which vice president Lyndon Johnson took the oath of office to succeed Kennedy. Kennedy's presidential library in Boston will launch a new exhibit of artifacts from his funeral and mark his death with music, excerpts of his speeches and a moment of silence. A Cape Cod coastal town near where his family still vacations will drape storefronts and a Kennedy museum in black bunting and hold a memorial mass. In Washington, a memorial mass will be held at the Cathedral of St. Matthew the Apostle while the John F. Kennedy Center for the Performing Arts will lay a wreath at his bust and discuss his legacy at the beginning of the evening's classical music performance. Museums, libraries, schools and churches across the country will also be marking his death with exhibits, lectures and memorials.