Donald Trump has been sworn in as the 45th President of the United States.

Mr Trump and his team will now embark on his avowed mission to undo many of the achievements of Barack Obama, including the monumental health care reform law, the Affordable Care Act.

“The movement continues - the work begins!” President Trump tweeted hours before the inauguration ceremony took place.

Mr Trump will enter the White House with the lowest favourability rating in four decades at 41.8 per cent – roughly half of Barack Obama’s 2009 rating.

Hundreds of thousands of people filled the streets of Washington DC to attend the inauguration ceremony, a number of whom were protesting the new President.

It is not unusual for activists to stage demonstrations during presidential inaugurations; however, the election of Mr Trump has been rife with contention and controversy.

At least one anti-Donald Trump protester smashed glass window frontage down the road from Capiol Hill (BBC)

Police try to remove demonstrators from attempting to block people entering a security checkpoint (AP)

Mr Trump, who lost the popular vote to Democratic nominee Hillary Clinton by nearly three million votes, is now tasked with leading a polarised country.

Despite this, the President’s top advisor, Kellyanne Conway, assured that he would take the opportunity to issue a call for unity.

“In the Inaugural Address, you will hear an uplifting, aspirational, visionary Donald Trump calling for us to take bold action fairly quickly,” she told CBS News. “That’s what businessmen do.”

Mr Trump’s election win caught many by surprise, as polls leading up to the final hours of Election Day indicated that former Secretary of State Clinton was the likely victor. And while she did secure a majority of individual votes, Mr Trump still earned a narrow majority in electoral votes.

Still, nothing was normal about the President’s campaign, which continuously surpassed the expectations of analysts, politicians, and even the public.

The campaign seemed dead on arrival when Mr Trump descended from the escalator of the gilded Trump Tower in June 2015. He launched a racist tirade against Mexican immigrants.

“When Mexico sends its people, they’re not sending their best,” he said. “They’re sending people that have lots of problems, and they’re bringing those problems with us.

“They’re bringing drugs. They’re bringing crime. They’re rapists. And some, I assume, are good people.”

To prevent such people from entering the US, Mr Trump repeated his promise to build a wall along the 2,000 mile border between the US and Mexico – despite the area already being heavily militarised, with large walls already covering major metropolitan points in the region.

Mr Trump saw a drop in polls after he accused an Indiana-born federal judge, who happens to be Mexican-American, could not be impartial in presiding over the fraud lawsuit involving Trump University.

“I’ve had terrible rulings, I’ve been treated very unfairly. Now, this judge is of Mexican heritage,” he said of US District Judge Gonzalo Curiel. “I’m building a wall. I’m building a wall.”

Mr Trump stoked concerns of civil liberties advocates when he announced an apparent outright ban on Muslim immigration to the US.

“Donald J Trump is calling for a total and complete shutdown of Muslims entering the United States until our country’s representatives can figure out what is going on,” a statement on his campaign website still reads.

Despite the controversy of Mr Trump’s unexpected rise, Barack Obama continuously reassured Americans that the peaceful transition of power was important to maintain to preserve democratic norms.

“There’s a difference between the normal functioning of politics and certain issues where I think our core values may be at stake,” he told reporters in his final press conference as President.

In his farewell letter to Americans, Mr Obama added that they have their work cut out for them, but that he would never be too far.

“I’ll be right there with you every step of the way,” he said.

Trump Inauguration protests around the World Show all 14 1 /14 Trump Inauguration protests around the World Trump Inauguration protests around the World Activists from Greenpeace display a message reading "Mr President, walls divide. Build Bridges!" along the Berlin wall in Berlin on January 20, 2017 to coincide with the inauguration of Donald Trump as the 45th president of the United State Getty Trump Inauguration protests around the World An activist holds up a sign at the "We Stand United" rally on the eve of US President-elect Donald Trump's inauguration outside Trump International Hotel and Tower in New York on January 19, 2017 in New York Getty Trump Inauguration protests around the World Protesters burn a U.S. flag and a mock flag with pictures of U.S. President-elect Donald Trump outside the U.S. embassy in metro Manila, Philippines Getty Trump Inauguration protests around the World Filipino protestors hold placcards during a protest rally in front of the US embassy in Manila, Philippines, 20 January 2017. On the eve of President-elect Donald Trump's inaguration as the 45th president of the United States, Filipinos and Fil-Americans held a protest in front of the US embassy in Manila to denounce the incoming US president. Getty Trump Inauguration protests around the World Hong Kong police officers and security guards look on as an anarchist protester belonging to the Disrupt J20 movement sits after using a heavy duty D-lock and motorcycle lock to chain himself to a railing at the entrance gate to the Consulate General of the United States of America in Hong Kong to protest the inauguration of United States President-elect Donald Trump, Hong Kong, China, 20 January 2017. Two activists were arrested and taken away by Hong Kong police during the demonstration. Getty Trump Inauguration protests around the World A banner is unfurled on London's Tower Bridge, organised by Bridges Not Walls - a partnership between grassroots activists and campaigners working on a range of issues, formed in the wake of Donald Trump's election, which aims to build bridges to a world free from hatred and oppression. Getty Trump Inauguration protests around the World Protesters chain themselves to an entry point prior at the inauguration of U.S. President-elect Donald Trump in Washington, DC, U.S. Getty Trump Inauguration protests around the World Bridges Not Walls banner dropped from Molenbeek bridge in Brussels, Belgium, 20 January 2017, in an Greenpeace action part of protests Wolrd protest in solidarity with people in the US, the day Donald Trump sworn in as the 45th President of the United States. Getty Trump Inauguration protests around the World A woman holds an anti-U.S. President-elect Donald Trump placard during a rally in Tokyo, Japan, Getty Trump Inauguration protests around the World A Palestinian protester holds a placard during a demonstration against the construction of Jewish settlements in the occupied West Bank and against US President-elect Donald Trump, on January 20, 2017, near the settlement of Maale Adumim, east of Jerusalem Getty Trump Inauguration protests around the World Banners on North Bridge in Edinburgh as part of the Bridges Not Walls protest against US President Donald Trump on the day of his inauguration Getty Trump Inauguration protests around the World Russian artist Vasily Slonov (L) and his assistant carry a life-sized cutout, which is an artwork created by Slonov and titled "Siberian Inauguration", before its presentation on the occasion of the inauguration of U.S. President-elect Donald Trump, in a street in Krasnoyarsk, Russia Getty Trump Inauguration protests around the World A woman holds a banner during a march to thank outgoing President Barack Obama and reject US President-elect Donald Trump before his inauguration at a park in Tokyo, Japan, 20 January 2017. EPA Trump Inauguration protests around the World Palestinian demonstrators protesting this week against a promise by Donald Trump to re-locate the US embassy to Jerusalem Reuters

“And when the arc of progress seems slow, remember: America is not the project of any one person. The single most powerful word in our democracy is the word 'We.' 'We the People.' 'We shall overcome.'