A minute's silence has been held across the UK to remember the 38 people - including 30 Britons - killed in the Tunisia beach attack a week ago.
The Queen and Prime Minister David Cameron joined the silence, along with the families of the dead.
Tourists and Tunisians gathered at the scene of the attack in Sousse, where they linked arms to observe the pause.
Inquests into the deaths of the Britons are under way, while the bodies of more victims have arrived in the UK.
At noon the nation fell silent, with businesses, sporting events and places of worship pausing to mark the moment the killings took place.
Tears were shed as hundreds of employees observed the silence at the head office of the travel company whose customers made up the toll of British dead, while flags were flown at half mast on many official buildings.
Walsall Football Club fell silent to remember three generations of one family who were killed.
Fans Joel Richards, 19, his uncle Adrian Evans, 44, and grandfather Charles (known as Patrick) Evans, 78, were among the dead.
Mr Richards's 16-year-old brother Owen survived the attack and was joined at the club's stadium by his mother Suzanne and hundreds of supporters.
Hundreds gathered to pay their respects to Adrian Evans outside Sandwell Council's offices, in the West Midlands, where he had worked as a gas services manager for many years.
"It's such a sad, sad fact that we are having to do this today but we wanted to demonstrate that Adrian Evans was one of our own," said council leader Darren Cooper.
"We are a very, very united community here and I've had expressions from various faith communities about the appalling nature of what has happened in Tunisia."
The Queen and Duke of Edinburgh joined staff in marking the silence at the University of Strathclyde during an official visit to open a new technology and innovation centre, while Mr Cameron observed the pause at his Oxfordshire constituency of Witney.
The ceremony held at the beach-side scene of the killings was attended by Tunisians, tourists and dignitaries - including Tunisian Prime Minister Habib Essid.
Mr Essid has told the BBC the slow response of police to the attack was a major problem. He also said he was deeply sorry for the killings.
The British ambassador to Tunisia, Hamish Cowell, laid a wreath on the beach. He said it was "very important to be here in Sousse one week after this appalling, cowardly attack, to remember all those who have lost their lives".
The silence was also observed at the headquarters of the TUI Group travel company in Luton, which owns Thomson and First Choice. All 30 Britons killed were its customers.
Of the 1,800 people on site, about 1,600 stood outside to pay their respects.
The BBC's Ben Geoghegan said some of those gathered in the company's car park wore black ties, while some dabbed away tears.
Passengers and crews on Thomson Airways flights and in TUI offices around the world also fell silent to remember the dead.
A number of mosques observed the silence, including at Birmingham's Central Mosque where more than 6,000 people took part.
Chairman Mohammad Afzal said: "In the Quran it says killing an individual is like killing the whole of humanity. These innocent holidaymakers have committed no sin, had done nothing wrong and their lives were as precious as any other."
Qari Asim, an imam in Leeds, said his mosque wanted to show solidarity with the victims' families, as well as paying "our tribute to the survivors, whose courage and determination still continues to inspire us".
Police officers across the country took part in the silence, while at Wimbledon matches started late to allow the minute's quiet to be observed.
And the silence was also marked at Silverstone, which is hosting the British Grand Prix on Sunday, led by drivers and teams and also observed by the crowds in the grandstands.
Hundreds of people gathered along the gates of Buckingham Palace and lined the nearby pavements during the silence.
And the touring Australia Ashes cricket team joined Essex players and officials to bow their heads during a break in play in Chelmsford.
At the scene in Sousse
By Thomas Fessy, BBC News
The Tunisian prime minister and several government ministers came along with ambassadors from the UK, the US, France, Portugal, Ireland and the Netherlands.
Representatives from Belgium, Canada and Libya also attended the brief commemorative gathering. They all arrived in silence, laid wreaths of flowers in front of the plaque erected on the crime scene before two trumpets gave a solemn salute.
Dozens of tourists had come to pay respects too. Most of them attended in their swimsuits with beach towels wrapped around their waists.
The smell of sun cream floating around was a strange reminder of the 38 people who were killed here, most of them lying on sunbeds, enjoying some relaxing holiday time.
Dignitaries left without a word while tourists and Tunisians - some of whom were hotel staff - formed a human chain, holding hands around the flowers that were laid in the sand throughout the morning.
'Time will heal'
The first inquests at West London Coroner's Court have been opened by Coroner Chinyere Inyama, and will be adjourned later.
During one of the hearings, the coroner heard Stephen Mellor from Bodmin, Cornwall, was killed by gunshot wounds to the chest and abdomen as he shielded his wife Cheryl.
Further inquests are due to be opened at the court on Saturday and Sunday.
Post-mortem examinations will be carried out before the bodies are released to their families.
The bodies of 25 of the British victims have now been returned to the UK.
The Foreign Office said those repatriated on Friday were Christopher and Sharon Bell, Scott Chalkley, Sue Davey, Angie and Ray Fisher, Eileen Swannack and John Welch.
The C-17 aircraft carrying their bodies landed at RAF Brize Norton on Friday afternoon.
The repatriation of the dead is likely to take several days, with two further flights planned for Friday and Saturday.
Among the three Irish citizens killed in the attack were Larry and Martina Hayes, who were buried in Athlone, in the Midlands Region, on Friday - which was the 30th birthday of their only daughter, Sinea.
Other victims included two Germans, one Belgian, one Portuguese and one Russian national.
Background and analysis
Tunisian authorities have identified 28-year-old Tunisian student Seifeddine Rezgui as the gunman who carried out the attack.
They are also holding eight suspects in custody on suspicion of being directly linked to the attack, which jihadist group Islamic State has claimed. Four others who were held have been released.
Scotland Yard has previously said its investigation into the attack is likely to be one of the largest counter-terrorism deployments since the London 7/7 bombings in 2005, which killed 52.