The Lockerbie bombing is being marked at home and abroad by senior politicians and officials 25 years after the terrorist atrocity killed 270 people.
The British Government is sending Scotland Office minister David Mundell to a memorial ceremony on Saturday in the US, where most of the victims were from.
"I am pleased to represent the UK Government at the memorial service in Arlington National Cemetery," said Mr Mundell, MP for Lockerbie.
"The memorial service will provide time to pause for thought and remember the loss of life on that tragic night."
A cairn of red sandstone, one brick for every life lost, stands at the cemetery in Virginia. The blocks come from Corsehill Quarry in Annan, Dumfriesshire.
Scotland's First Minister Alex Salmond will attend a ceremony at Dryfesdale Cemetery in Lockerbie. Lord Wallace, Advocate General for Scotland and former Scottish Liberal Democrat leader, will also attend.
A service will be held at Westminster Abbey at the same time as commemorations in America, attended by Scottish Secretary Alistair Carmichael and Scotland's Deputy First Minister Nicola Sturgeon.
Pan Am flight 103 exploded above Lockerbie, in southern Scotland, on the evening of December 21 1988, killing all on board and 11 people on the ground.
Much of the focus is on America, where 189 of the victims on the Boeing 747 were from.
Forty-three victims on the plane and in the town were from the UK, with a further 19 nationalities among the dead.
The bombing was a truly international incident, ultimately leading to two Libyan suspects being sent to trial at a special Scottish court in the Netherlands.
Only one man, Abdelbaset al-Megrahi was convicted of the bombing. He was found guilty in January 2001 and given a life sentence.
Megrahi was diagnosed with prostate cancer in 2008, leading to a pivotal decision to free him under compassionate release rules.
Scottish Justice Secretary Kenny MacAskill took that decision on August 20 the following year, sparking a huge row among politicians on both sides of the Atlantic.
Megrahi died in Tripoli in May last year.
Despite the guilty verdict and Megrahi's decision to drop a subsequent appeal against conviction, politicians, campaigners and families of victims are still dealing with the impact.
A petition by pressure group Justice For Megrahi has been inching through the Scottish Parliament with calls on the Government to open an inquiry into the conviction.