Europe began a final countdown Sunday to the launch of what will be the continent's most widely used common currency since the Roman Empire.

At a glittering ceremony in Brussels, an electronic clock began ticking down the final 2002 minutes to the historic launch of euro notes and coins today.

The event also marked the transfer of the European Union's rotating presidency from Belgium to Spain, which officially takes the helm on the same day that the euro sweeps away the currencies used until now by 300 million Europeans in 12 countries.

"The euro is the symbol of the strength of our union,'' Spanish Prime Minister Jose Maria Aznar said at the ceremony, which was attended by King Juan Carlos of Spain and Belgium's King Albert II.

"In less than two days, more than 300 million people will use the same currency in a zone stretching beyond Lisbon, Helsinki, Dublin and Athens,' ' Belgian Prime Minister Guy Verhofstadt said, speaking amid the sparkling chandeliers and red velvet curtains of Brussels' royal palace.

January 1 marks the culmination of a dream long held by European visionaries and one of the most significant steps in the building of the 15-nation EU.

The people of 12 EU nations will share the same currency, making it easy to compare prices throughout the bloc, eliminating the need for costly currency exchanges for travelers and creating a powerful unifying political symbol.

Three EU nations -- Britain, Sweden and Denmark -- have opted out of the initial launch but the currency will be accepted in some British shops and will play an influential role in world trade.