In pictures: World War One anniversary

Ceremonies have been held across the UK and in Belgium to mark 100 years since Britain joined World War One.

A column of white light projected into the sky above Westminster Abbey, in London

In pictures: WW1 anniversary

A service was held at Westminster Abbey, in London, where a light installation called Spectra beamed a column of white light into the sky while a candle-lit prayer vigil was held inside.

The congregation at a service in Westminster Abbey hold candles

The service of solemn commemoration was attended by the Duchess of Cornwall, where members of the congregation held candles.

A lantern being placed at the front door of Number 10 Downing Street

Across the country lights were switched off and candles were lit, in churches and places of worship, public buildings and homes among other premises, including outside Number 10 Downing Street.

Lights switched off at the Houses of Parliament

The lights were switched off at the Houses of Parliament, as part of the UK-wide "Lights Out" event recalling then-foreign secretary Sir Edward Grey's remark on the eve of the outbreak of war: "The lamps are going out all over Europe; we shall not see them lit again in our lifetime."

A candle is lit as the London Eye on London's South Bank has its lights switched off

Candles were lit across the UK to mark the centenary, while the London Eye, in London's South Bank, was plunged into darkness.

World leaders commemorate the 100th anniversary of the outbreak of World War One

Meanwhile, the Duke and Duchess of Cambridge, Prime Minister David Cameron and Prince Harry were among the dignitaries to attend a twilight ceremony at the St Symphorien Military cemetery, near Mons, Belgium.

The Duke of Cambridge (centre) and David Cameron (2nd right) lay flowers at the ceremony.

Dignitaries, including Prince William and Mr Cameron, laid loose flowers as a mark of respect at the ceremony - rather than wreaths or poppies, which became a tradition after the end of World War One.

The Queen attends a service at Crathie Kirk Church in Crathie, Aberdeenshire

The Queen was also among those to pay their respects in Scotland when she attended a memorial service at Crathie Kirk in Aberdeenshire.

Prince Harry, Mons city mayor Nicolas Martin, Prince William and the Duchess of Cambridge appear on a balcony at the Mons townhall with Belgium's outgoing Prime Minister Elio Di Rupo

Crowds gathered at the town hall in Mons to greet the Duke and Duchess of Cambridge and Prince Harry as they appeared on the balcony.

A message on a wreath laid by Prime Minister David Cameron is seen at the Cenotaph in Glasgow

A message on a wreath laid by PM Mr Cameron in Glasgow earlier read: "Your most enduring legacy is our liberty. We must never forget."

The Duke and Duchess of Cambridge and Prime Minister David Cameron arrive for a commemoration ceremony at the St Symphorien Military Cemetery in St Symphorien, Belgium

The royal couple also made a private visit to see the graves of UK, Commonwealth and German soldiers at St Symphorien Military Cemetery in Mons.

Members of the Great War Society surrounded by poppies

Members of re-enactment group the Great War Society were showered by poppies in a ceremony at the Tank Museum in Bovington, Dorset, on Monday.

The Queen and King of Belgium stand alongside the Duke and Duchess of Cambridge

The King and Queen of Belgium met the Duke and Duchess of Cambridge at a ceremony in Liege where commemorations have been taking place.

A veteran arrives at a parade in Folkestone, Kent, to mark Monday's anniversary

A military veteran was one of many attending events in Folkestone, Kent, where Prince Harry unveiled a memorial arch to honour the fallen.

The Duke of Cambridge

Speaking in Liege, Prince William described the Belgian people's resistance "as gallant as their suffering was great".

King Philippe of Belgium is handed a balloon by a girl dressed in white in Liege

King Philippe of Belgium was met by a girl dressed in white in Liege.

King Philippe of Belgium (far left) lays a wreath

King Philippe of Belgium (far left) prior to laying a wreath in Liege, which was once seen as the most fortified spot in Europe.

The Duke and Duchess of Cambridge with Francois Hollande

The Duke and Duchess of Cambridge spoke to French President Francois Hollande at the ceremony.

Bands from Germany, dressed in grey, and Belgium (right) performed for dignitaries attending the ceremony in Liege.

Bands from Germany, dressed in grey, and Belgium (right) performed for dignitaries attending the Liege event.

Balloons in Liege

Thousands of balloons were released over the Belgian city as the ceremony drew to a close.

Prince Harry meeting members of the armed forces in Kent

Prince Harry laid a wreath and met members of the armed forces during a visit to Folkestone, Kent.

Woman at Folkestone, Kent, commemorations

A woman sheltered under her umbrella ahead of those Kent commemorations.

Balloons decorated with poppies

Also in Folkestone, balloons decorated with the emblem of a poppy and carrying the name of a fallen soldier were released into the sky.

Folkestone commemorative march

The town also saw veterans and soldiers parade past a sign written in English, French and German.

Chelsea Pensioners in London

Chelsea Pensioners have also been commemorating the anniversary with a central London parade.

The Tower of London moat with 888,246 ceramic poppies

The Tower of London moat has been turned red by 888,246 ceramic poppies, one for every British and Commonwealth soldier killed during the conflict.

Prince Charles also attended the commemoration ceremony in Glasgow.

Prince Charles attended Glasgow Cathedral for a service - alongside many Commonwealth figures - where he signed a commemoration book.

100 white crosses outside New Zealand parliament

Elsewhere, 100 white crosses have been placed outside New Zealand's parliament building in Wellington, in memory of the more than 18,000 New Zealand troops killed in WW1.

The memorial arch during the Step Short commemorative event in Folkestone, Kent to commemorate the 100th anniversary of the outbreak of World War One

A memorial archway in Folkestone, unveiled by Prince Harry, marks the role the Kent port town played in World War One. It became known as the gateway to the trenches as the location millions of soldiers began their voyage to France.

WW1 photo recreated

On its Twitter feed, the British Army published a photo of The Queen's Dragoon Guards in Afghanistan (right) recreating an image of soldiers moving up the trenches in 1914.

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