WW1 centenary events by World leaders in UK and Belgium
Royals and world leaders have gathered for ceremonies marking 100 years since Britain joined World War One.
The Prince of Wales and David Cameron attended a service in
Glasgow, while the Duke and Duchess of Cambridge are in Belgium with
many heads of state.At that ceremony, Prince William paid tribute to the soldiers who "died to give us our freedom".
The day concludes with a candle-lit vigil at Westminster Abbey and a "lights out" event around the UK.
The public can join the switch-off ending at 23:00 - the time Britain declared war on Germany in 1914.
About 17 million soldiers and civilians were killed between 1914 and 1918.
'Deadly days' The day's events began in Liege, Belgium, where 50 heads of state gathered for a service to mark the invasion of Belgium.
French President Francois Hollande said the country had been the first battleground of WW1 and had offered "solid resistance" in Liege.
"Deadly days" followed when French and British soldiers joined the conflict, he said.
David Cameron gave a Bible reading at Glasgow Cathedral earlier, in a service attended by Prince Charles
Prince Harry laid a wreath and unveiled a new memorial arch in Folkestone, Kent
"We salute those who died to give us our freedom. We will remember them."
Meanwhile, the service at Glasgow Cathedral - attended by Prince Charles, Mr Cameron, First Minister Alex Salmond, and 1,400 others - heard from a number of Commonwealth figures.
The BBC's Laura Bicker said Sunday's closing ceremony of the Commonwealth Games was being discussed by many before the service - but the celebrations were "put to one side" as the congregation took time to "remember and reflect".
Prince Harry unveiled a memorial arch in Folkestone, Kent - where a parade followed the route taken by millions of soldiers who marched to the harbour to begin their voyage to France in WW1.
The beautiful military cemetery at St Symphorien has been transformed.
Across the boundary fence, in what is normally empty farmland, a great grandstand has risen, overlooking the graves of the first and the last British soldier to die in World War One.
Cables snake around the gravestones of British and German soldiers, laid here side by side after the battles that raged around Mons on summer days in 1914.
St Symphorien has become an arena, overlooked by a worldwide audience, where Monday evening's televised event will mark personal sacrifice and celebrate new friendships.
Under the pine trees, David Wood had come to find the grave of his great-uncle, killed 10 days after arriving in Belgium, aged 23.
Standing in front of the headstone with his daughter, Mr Wood said he was proud to be here on this anniversary.
The families who have travelled here from Britain and Germany share those sentiments.