VATICAN CITY (CNS) -- No one would ever mistake St. Peter's Square for Giants Stadium. But for centuries, the Vatican has hosted countless competitions and dozens of high-caliber athletes -- most of them lay employees, some of them monsignors and popes. Because so few people know about the sporty side of the Vatican and because much of it is oral history that needs to be preserved, one Vatican employee has decided to publish his research. Roberto Calvigioni, department head of sound engineering at Vatican Radio, spoke with the Vatican newspaper, L'Osservatore Romano, this summer about the soccer champs, black belts, tennis aces and cycling stars who will appear in his book, which, he explained, is still in the works. Pope John Paul II obviously stands out as the most athletic pope in memory: He was an avid skier, soccer player, swimmer and hiker. Pope Pius XI loved mountaineering. He was the first to summit Switzerland's highest mountain, Monte Rosa, from the eastern slope.