A series of celebrations have been planned to mark the 500th birthday of Aberdeen's ''Mither Kirk'' in the heart of the city.

There has been a church on the St Nicholas site since around 1160 but it was in 1498 that Bishop Elphinstone, Aberdeen University's founder, dedicated the church.

In those days, it would have been surrounded by fields with a clear view out to sea. Now it sits in the middle of Union Street and Aberdonians regularly enjoy lunchtime picnics in the graveyard in which so many of their eminent predecessors lie.

In fact, a Grampian Enterprise survey revealed that most Aberdonians regarded the graveyard as the ''centre of Aberdeen''.

St John's Chapel in the kirk, where a book is kept bearing the hand-written names of the 167 Piper Alpha victims, was refurbished by the oil industry in 1990 but its walls, the oldest masonry in Aberdeen, date back to the twelfth century.

As well as announcing a programme of events yesterday, a #50,000 appeal was launched. The money will be used to restore the great south window in the Drum Aisle and to buy furnishings to display the kirk's artefacts, souvenirs and pamphlets.

There will be a programme of musical events and a commemorative service in the kirk on September 24 attended by the Moderator of the General Assembly at which a Coat of Arms petitioned for by the kirk will be presented.

A commemorative dinner is also to be held, four former ministers will preach during the year and there will be a special service for couples married at St Nicholas.

Launching the appeal, Lord Provost Margaret Farquhar said the relationship between the kirk and the council went back to 1277 when her earliest known predecessor, Richard Cementarius, is recorded as being a benefactor of the kirk.

She revealed that although the dedication of the kirk took place in 1498 planning began in 1442 and civic taxation on a regular basis for the project started in 1449 making it one of the lengthiest civic projects in the history of the burgh.

Among those buried there are Elizabeth Crombie Duthie, who gifted the city the land which became the Duthie Park and William Hay, who discovered the success of the application of superphosphate of lime to turnips.

Nearby lies John Anderson, a blacksmith who became famous as the ''Wizard of the North'', a great illusionist and showman.