Orthodox nuns: Their church has been in schism with Rome since 1054

Vladimir heard that there was this religion called Christianity, but there were two rival capitals of the Christian world - one in Constantinople and one in Rome.

In order to make a reasoned choice over which branch of the Christian religion he should choose, the prince sent ambassadors to report on how Constantinople - the modern Istanbul - and Rome measured up.

The envoy he sent to Rome reported that the prestigious former capital of a huge empire stretching all the way from Scotland to Arabia was reduced to a sorry state.

Rome's magnificent secular and sacred buildings had been vandalised and had fallen into disrepair. The population of the city was tiny.

Christian Ukraine

50 AD: St Andrew preaches in region 988 AD: Christianity made state religion 1054: Great Schism 1596: Ukrainian Catholic Church unites with Rome

The ambassadors who visited Constantinople were bowled over by the magnificence of the city they saw.

The golden domes, the Byzantine church of Saint Sophia, imperial palaces, Christian shrines of incomparable beauty.

The ambassadors thought they heard the angels singing, they reported.

The year was 988, and Vladimir opted for Constantinople.

He ordered all his subjects to be baptised in the River Dnieper in Kiev and the die was cast.

'Great Schism'

As Christianity spread over eastern Europe, some rulers opted for what became known as the orthodox religion of Constantinople, while others pledged their allegiance to the Pope in Rome.

The Pope hopes to visit Moscow before he dies

Less than a century later, that great divide between Catholics and Orthodox Christians had become an unbridgeable gap - the two churches excommunicated each other's followers in 1054.

This became known as the Great Schism.

Pope John Paul is today attempting to bridge the deep divide among Ukraine's Christians that is rooted in Prince Vladimir's choice of more than a millennium ago.

And that's why the Pope is so keen to visit Moscow - the new capital of the land of Rus - before he dies.

In private, John Paul has referred longingly to Moscow as the Third Rome.