Pope John Paul II celebrated a special Mass in St. Peter's Basilica to mark the 25th anniversary of the Second Vatican Council. "The council accomplished an immense work," John Paul said, speaking from the same pulpit that Pope John XXIII used to inaugurate Vatican II on Oct. 11, 1962. But he said that some council reforms have yet to be implemented adequately. The council was held from 1962 to 1965 in four sessions attended by more than 3,000 prelates and theologians. It introduced wide-ranging reforms, many of them still the object of debate between liberal and conservative Roman Catholics.