A group of about 150 people in black face masks were seen by Reuters news agency, roaming the streets and smashing glass windows only moments ago.

One person held a sign saying Make Racists Afraid Again.

We don't yet know what organisation the violent protesters represent.

Alli McCracken, 28, said protesters for a liberal group called Disrupt J20 intended to show it's opposition to Trump's statements on illegal immigrants, women and Muslims.

"We have a lot of people of diverse backgrounds who are against US imperialism and we feel Trump will continue that legacy," McCracken said.

We are streaming from the build-up to the ceremony at the Capitol...

The US consulate in Montreal has issued a "security message" for American citizens to be alert around protests planned in that city.

"Even demonstrations intended to be peaceful can turn confrontational and escalate into violence. You should avoid areas of demonstrations, and exercise caution if in the vicinity of any large gatherings, protests, or demonstrations," the consulate posted online.

In Canada, anti-Donald Trump protests are planned across the country on Friday and Saturday.

Image source, Getty Images

Hillary, accompanied by Bill, is wearing her trademark pantsuit, snow white.

The BBC's James Cook ran into some aggressive protesters last night.

Dozens of different activist groups have come to the capital, some apparently with violent intent.

One group, Disrupt J20, has been trying to block security checkpoints to prevent Trump supporters from getting access to the viewing area on the National Mall. 

WARNING: Graphic language in video below.

Tensions are running high in parts of the capital. Black-clad protesters have thrown bins on the street and smashed the windows of shops.

Security guards closed one parade entrance after it was targeted by a Black Lives Matter protest. 

Protesters chanted "f*** Trump" and linked arms to prevent people gaining access. Trump supporters shouted back at the protesters. 

Dan Quayle and Dick Cheney are in position.

The BBC's Tara McKelvey has been talking to people on the DC streets.

"We hope the new president will take the world to peace," says Chanty Sem, a Cambodian who lives in Phoenix. 

Nearby people are heading to the mall, and the streets smell like marijuana.  

Meanwhile, Raymond Garcia, a retired engineer from Houston, is visiting his grandchildren in Washington. 

He says he didn't vote for Trump, but he is supporting him now. 

"Not everything is the way you want it to be," he added.

As noted earlier, protesters supporting the legalisation of cannabis have been handing out free samples of the drug near the inauguration.

Washington DC voters chose to legalise the use of marijuana in 2014, and giving it away is legal inside the city as well.

However the federal government still views it as criminally illegal, and we have yet to see how the Trump administration will approach the issue. 

Alex Wellerstein, a nuclear historian, spotted this pilot from the window of his Big Apple apartment this morning. 

The aerial advertising banner reads: "We outnumber him! - Resist!"

How long will Trump's inaugural address be? 

The shortest was by the first US President, George Washington, clocking in at a mercifully brief 133 words.

Hillary Clinton, the Democratic presidential candidate who suffered a shock defeat to Trump, has arrived at the US Capitol. This was the day she had dreamed of being inaugurated as the first US female president. It must be tough...

Watching a rival being sworn in from up close has happened several times in American history, including when outgoing Vice-Presidents Richard Nixon in 1961 and Al Gore in 2001 watched from the risers as the men who had beaten them to the presidency raised their hands for the oath of office.    

For over a decade the majority of Americans have felt the nation is growing increasingly divided each year.

On the eve of Trump's presidency, that figure is at an all-time high.

Pew Research Center found that 86% of people consider the country more divided than it was in the past. 

When Obama first took office in 2009 only 46% felt that way.

Only about a quarter of respondents (24%) expect the country’s political divisions to subside any time soon.

More from BBC correspondents on the global contrasting emotions surrounding Trump's inauguration.

In Russia, parties have been held to welcome the new White House incumbent, as Moscow hopes for better bilateral ties under Trump, the BBC's Sarah Rainsford reports.

She says Trump posters can been seen on Moscow streets, and there are even "Trump burgers" and "Trump lollipops" on sale... 

Image source, EPA

...while in Mexico, ordinary people and politicians have been reacting with disgust to Trump's ascension to power, the BBC's Will Grant reports.

The first potential clash in bilateral ties will be the issue of the so-called "Mexican Wall" Trump has promised to build using Mexico's money.

International media are in Washington DC covering today's events.

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The BBC's James Cook reports that up to 200 anarchists are protesting at Logan Circle in Washington DC, many wearing masks and dressed in black.

Meanwhile the BBC's Hetal Gandhi reports on how Trump supporters in Washington are reacting to protesters.

...our reporter also noticed that Trump merchandise is selling like hot cakes...

Anthony Zurcher
BBC North America reporter

Columnist Mark Shield has observed, external that when choosing a new president, American voters often appear drawn toward candidates who have attributes their predecessor in the Oval Office seemingly lacked.

Machiavellian Richard Nixon was replaced by do-gooder Jimmy Carter. Bill Clinton’s unchecked appetites gave way to teetotaller George W Bush, whose perceived lack of eloquence stood in sharp contrast to next-in-line Barack Obama’s erudition.

Now Obama, criticised even by some supporters as being overly professorial and detached, is handing over the reins of power to a man known for blunt bombast and raw emotion. It’s a dramatic swing of presidential temperament that will be matched by the seismic political changes that loom over the coming days.

For the past two years, Obama and the Democrats in the Executive Branch have served as a check on Republicans in Congress. With threat of a presidential veto and the broad powers federal agencies possess, they’ve managed to keep the Obamacare health insurance system intact, adjust immigration law enforcement, impose new environmental regulations to address climate change and maintain the closer oversight of the financial sector set out in banking reform laws passed in 2009.

Those days are over.

For the first time in 10 years, the Republicans will have unified control over the federal government. They have the opportunity to advance their agenda – and roll back Obama’s legacy – on a wide variety of fronts. The biggest challenge facing Trump and his party on this rainy January Inauguration Day is where exactly to start.

The digital freeway announcement board in the US state of Maryland, where some of Washington DC suburbs extend, makes a wise crack about the traffic around the US capital city today.