20 February 2015
Last updated at 16:01
More than 100 people died in the Maidan clashes, with most of them being shot by snipers
The Ukrainian capital, Kiev, is marking the first anniversary of the clashes between protesters and police which toppled ex-President Viktor Yanukovych.
More than 100 people died in the violence on the Maidan – Kiev’s central Independence Square – a year ago.
The anti-Yanukovych revolt was called the “EuroMaidan revolution”, as huge crowds demanded a pact with the EU.
Pro-EU President Petro Poroshenko will address the nation, after setbacks for the military in the eastern conflict.
Pro-Russian rebels pushed his army back from the key town of Debaltseve two days ago.
After Mr Poroshenko’s speech there will be a concert on the Maidan, including poetry, a choir singing the national anthem, and a performance of Mozart’s Requiem by the National Symphony Orchestra of Ukraine.
Mr Yanukovych – a political ally of Moscow – fled into exile in late February 2014, but soon resurfaced in the southern Russian city of Rostov-on-Don.
He said he had been ousted in an “illegal coup” and lambasted the “fascists” who had taken power in Kiev.
For weeks in the bitterly cold winter of 2013-2014 the Maidan was a vast campsite populated by the EuroMaidan protesters, who kept police at bay with barricades and burning tyres.
Most of those killed in the Maidan clashes were shot by snipers, and some uniformed police were filmed firing at protesters.
Analysis: Anastasiya Gribanova, BBC News, Kiev
Ukrainians will remember 20 February for many years to come.
It became the tipping point for the anti-government protest that had gained momentum all winter.
What started as a peaceful rally against President Yanukovych’s decision to steer Ukraine off its pro-European path morphed into a fight against the corrupt government. It ended in a violent stand-off between riot police and protesters.
Mr Yanukovych’s rule came to an abrupt end, but the price was high – more than 100 people killed in the clashes. They are now remembered as the “Heavenly Hundred”.
Many of them died on 20 February, the last and most dramatic day of the protests.
A year on, people are coming to the Maidan again to honour those who gave their lives fighting for a better Ukraine.
A ceasefire for war-torn eastern Ukraine, signed in Minsk on 12 February, looks fragile as shelling continues in some areas. An intense rebel bombardment forced some 2,500 government troops to retreat from Debaltseve on Wednesday, and dozens of others surrendered.
The village of Chernukhino, near Debaltseve, is now in rebel hands too, the Kiev-appointed governor of Luhansk region, Gennadiy Moskal, said on Friday.
The Ukrainian government, Western leaders and Nato say there is clear evidence that Russia is helping the rebels with heavy weapons and soldiers. Independent experts echo that accusation. Moscow denies it, insisting that any Russians serving with the rebels are “volunteers”.
A Ukrainian military spokesman, Andriy Lysenko, said more than 20 Russian tanks, 10 missile systems and busloads of troops had entered Ukraine in the past 24 hours, heading for Novoazovsk, a rebel-held town on the coast.
French President Francois Hollande, who helped broker the Minsk deal, said “I have no confirmation of armoured vehicles entering – that doesn’t mean it isn’t the case”.
“The ceasefire has been violated several times, notably in Debaltseve, but it must be observed in full,” he told a news conference.
German Chancellor Angela Merkel, who negotiated alongside Mr Hollande in Minsk, said the OSCE security body “must have access, so that heavy weapons can be withdrawn” in line with the ceasefire deal.
She warned that further EU sanctions could be imposed on Russia if ceasefire violations were proven, “but the aim of Minsk was not sanctions”.
At the scene: Paul Adams, BBC News, Debaltseve
The streets of Debaltseve were mostly quiet and mostly deserted as we entered the city for the first time since intense fighting ended.
Those civilians still holed up in the city, who have been without water, gas and electricity since early January, were slowly emerging from shelters to see what was left of their homes.
But there were more rebels than civilians, with convoys of victorious separatists returning from the recent clashes.
Evidence of the fighting was littered across the roads and we spotted the bodies of two Ukrainian solders that had been lying in the cold for three days.
Do you live in eastern Ukraine or have friends and family in the region? What do you think about the recent developments? You can email [email protected] with your experience. Please include a telephone number if you are willing to be contacted by a BBC journalist.