BBC Correspondent Alex Kirby: For Karel Wojtyla the WWII changed everything

Pope John Paul II, who is 78, joins a mere dozen popes in history whose reigns have spanned two decades or more.

However the celebrations are being kept to a minimum with the Vatican keen to prevent the occasion from becoming a political obituary.

The pope has already issued a special message to the world's Catholics, appealing to humanity not to let itself be carried away by technology.

He urged people to pause and think in his 13th encyclical message

In a new encyclical letter, released to coincide with the anniversary, he said people should pause to ask themselves the true meaning of life. And with the millennium approaching, they should be discussing vital issues such as the environment, peace and the co-existence of different races and cultures.

In 1978 the world was stunned when the electoral college of cardinals chose the Polish Cardinal Wojtyla to lead the Roman-Catholic Church.

Inspirational figure

He broke nearly 500 years of Italian rule, then went on to become the most well-travelled pope in history, visiting more than 100 countries, including every country in Latin America.

BBC Religious Affairs correspondent Jane Little says he will go down as a key player of the 20th century, inspiring the Solidarity movement in his native Poland and helping bring about the demise of communism.

Controversial doctrines

More recently he has turned his attentions to the evils of unbridled capitalism.

Rome Correspondent David Willey: He is still capable of surprises

During his trip to Cuba earlier this year, he castigated the communist leader Fidel Castro for his poor record on human rights, but also criticised the United States for its trade embargo.

More controversially he has provoked dissent among many of the world's one billion Catholics, for his absolutist stance on church doctrine.

He attacked liberation theology in Latin America, has vehemently ruled out abortion, and contraception, despite the threat of Aids, and banned all discussion of allowing women into the priesthood.

But the Pope has also been a vocal defender of human rights, and despite ailing health in latter years, he has kept up a punishing schedule.

And Rome Correspondent David WiIley says he has reinvented the office of pope for modern times and is still capable of surprises. Just this week he made his first appearance on a phone-in show on Italian TV.

The longest pontificate - of Pius the Ninth - lasted 32 years. Even if he dones not match that, Pope John Paul is looking ahead, determined to visit holy sites in Israel and Iraq to see in the next millennium.