Chinese President Xi Jinping has said China does not oppress other countries, at a speech marking the 100th anniversary of the founding of the ruling Communist Party, reports BBC.
In comments seen as a reference to the US, Mr Xi also warned against anyone "oppressing China", saying they would "have their heads bashed... against a great wall of steel".
A vetted crowd of about 70,000 are in Beijing's Tiananmen Square.
Many of them are not wearing masks.
Mr Xi, who spoke for around an hour, also reiterated the role of the party in modern China, saying that it has been central to the country's growth story and that attempts to separate it from the people would "fail".
He added that "we will never allow anyone to bully, oppress or subjugate China".
China has repeatedly accused the US of trying to curb its growth - and these comments are also seen as a reference to Washington.
The ceremonies on Thursday morning also saw military jet fly-pasts, cannon salutes and patriotic songs played.
The country has seen a media blitz in recent weeks promoting a party-approved version of China's history.
Hong Kong is also marking its handover anniversary.
How has China prepared for this anniversary?
The Chinese Communist Party (CCP), which was founded in 1921, came to power 72 years ago after a long civil war.
In that time the country has undergone massive changes - but some of these milestones were conspicuously missing in the propaganda drive.
On Monday, an art performance titled The Great Journey was staged at the Bird's Nest stadium in Beijing, where performers put on extravagant set-pieces detailing the history of the party and country.
But significant events such the Cultural Revolution purges, the 1989 Tiananmen Square protests, and the pro-democracy protests in Hong Kong were missing, reported AFP news agency.
Since April, Chinese cinemas were ordered to screen propaganda films, known as "red films", at least twice a week.
Meanwhile, 100 television dramas celebrating the anniversary have been scheduled to broadcast throughout the year.
A song, called 100%, that praised China's achievements and featured 100 rappers was also released.
"Red tourism" has also become popular, with travel companies such as Ctrip launching 100 unique routes for "red pilgrims".
Several sites across the country deemed historically significant for the party, including former revolutionary base Yan'an city, have reported spikes in tourists.
But not all are pleased with the propaganda.
"Now when I turn on the TV at night, dozens of stations are airing dramas about revolutionary wars," a Beijing resident told BBC Chinese.
"Every day, it's all about building a party and building a nation - do you have any other choice?"
Why is the anniversary significant?
With celebrations focusing on the intertwining histories of the party and country, the CCP appears keen to make itself synonymous with China's rapid development, say experts.
The centenary is "clearly an important moment for the party and has been planned meticulously," Tom Rafferty from The Economist Intelligence Unit told the BBC.
"A consistent element in the official messaging has been the emphasis on the current period as representing a 'new era' distinct from the post-1978 reform period," he said, adding that this "underscores the ambitions of the current leadership".
But the centenary might not lead to any major announcements, say experts, who believe those may come at next year's party congress instead.
What about Hong Kong?
Thursday also marks the 24th anniversary of the former British colony's handover to Chinese rule.
Though the city usually holds celebrations, in recent years it has seen anti-Beijing protests on the date - though a controversial national security law put in place last year has muted dissent.
Hong Kong police have denied permission for a rally, citing coronavirus restrictions, organisers said.