At the site of the Greenwich Meridian Line, the pace is set which the world

follows, whether it be adjusting alarm clocks in Hounslow or timing a business meeting in Hong Kong.

Also known as the Zero Meridian, the line was chosen more than 100 years ago, at an international conference of 25 countries, to be the centre of a world time-zone system, and Greenwich Mean Time was born.

Without this barrier dividing am (ante meridiem) and pm (post meridiem), people waiting to celebrate the new millennium on the night of 31 December 1999 would have no way of knowing when the year 2000 officially begins.

The Meridian is used for time-keeping and navigation on land, sea and in space. It passes through the original site of the Royal Greenwich Observatory, which was moved to East Sussex in the 1950s. From there it stretches north through Cambridgeshire and Humberside to the North Pole, and south across France, Spain and the Sahara before running past Accra, capital of Ghana, en route to the South Pole.

The first people to experience the new millennium will be those just west of the International Date Line, Greenwich Meridian's opposite line which dissects the Pacific Ocean.

Residents of the islands of Fiji will be among those who will see dawn on 1 January 2000 ahead of the rest of the world. Britain will not start celebrating until 12 hours later when midnight arrives at the Zero Meridian.

(Photograph omitted)