Edinburgh's One O'Clock Gun celebrations begin
Celebrations to mark the 150th anniversary of Edinburgh's One O'Clock Gun are to start later.
The historic gun fires daily apart from on Sundays from Edinburgh Castle.
The first event is being held from 1245 GMT at Greyfriars Tolbooth and Highland Kirk where Greyfriars Bobby used to live during the 1800s.
Bobby the terrier dog was alerted it was time for dinner when he heard the One O'Clock Gun fired. Edinburgh's Lord Provost George Grubb will attend.
Mark Lazarowicz MP for Leith and Rev Dr Richard Frazer, Greyfriars Tolbooth and Highland Kirk's minister, will also each make an address.
George Robinson, spokesman for the One O'Clock Gun and Time Ball Association, said: "When the time gun was set up in 1861, Greyfriars Bobby used the One O'Clock Gun as a dinner signal.
"He would leave the Kirkyard when the time gun fired and go to a restaurant in Greyfriars Place for his food.
"Bobby was friendly with Colour Sgt Scott of the Royal Engineers who stayed in lodgings at 28 Candlemaker Row.
"Bobby would follow him along George IV Bridge when the soldier went to work at Edinburgh Castle.
"In 1867 the Dog Act was introduced which required that all dogs be licensed.
"The police believed that John Traill, the owner of Traill's Temperance Coffee House, was the dog's owner.
"Although John Traill was summoned to the Burgh Court he refused to pay for the licence.
"When Lord Provost of Edinburgh Sir William Chambers heard that Bobby was to be put down, he paid for the licence and bought him a collar."
Edinburgh's Lord Provost George Grubb said: "Edinburgh's One O'Clock Gun is famous all over the world and the city is now embarking on a series of events to celebrate its 150th anniversary.
"People have been setting their clocks and even ships' clocks by the gun's firing for generations.
"Greyfriars Bobby is thought to have used the gun as a signal for his lunchtime, so it's lovely that the anniversary events should start with a special service at Bobby's headstone."
Greyfriars Bobby died on 14 January 1872 and is buried in Greyfriars Kirkyard.