10am. National service of commemoration, Glasgow Cathedral, attended by Prince of Wales and David Cameron, followed by a procession to the cenotaph, George Square, for a wreath-laying service, and march-past at 11.30am.
10am. Great War centenary parade of Edwardian cars, central London, departing from Royal Chelsea hospital.
10.45am-1pm. Folkestone. Step Short parade including unveiling of memorial arch by Prince Harry on the Road to Remembrance where soldiers walked down to the harbour.
11am. Remembrance service, Cointe, Liege, Belgium, attended by international leaders joined by the Duke and Duchess of Cambridge.
11am. Women's International League for Peace and Freedom stage reconstruction of anti-war protest opposite Holborn tube, London, close to Kingsway Hall site where the original protest was made.
Morning. Queen attends commemorative service at Crathie Kirk near Balmoral. Prince Philip attends service at Sandringham, Norfolk.
5pm-9pm. National Memorial Arboretum, Alrewas, Staffordshire. Evening service and candlelit vigil.
6.15pm. Durham Cathedral, evening vigil.
7pm. St Anne's Cathedral, Belfast. Service attended by Theresa Villiers, Northern Ireland secretary, followed by candlelit vigil from 10-11pm at Belfast city hall.
7.30pm. Commonwealth War Graves Commission service at the St Symphorien military cemetery near Mons, Belgium where the fallen from both sides lie. David Cameron, Duke and Duchess of Cambridge and Prince Harry among international dignitaries to attend.
10pm-11pm. National. Lights Out. Lights to be turned off in homes, offices, public buildings across Britain with each leaving a single light or candle to mark the moment the UK entered WWI.
10pm-11pm. Bath Abbey, candlelit vigil.
10pm - 11pm. Westminster Abbey, service of solemn commemoration, culminating in the extinguishing of candles one by one except for a single burning oil lamp on the tomb of the Unknown Warrior.
