Washington – A new chapter in the history of the United States begins today, Friday, as Donald Trump will officially be sworn in as the 45th president.

A succession of ceremonies and parades will mark the day, with the presence of four former U.S. presidents and first ladies, in addition to international diplomatic delegations, senators, lawmakers, entertainment stars and public figures.

The U.S. Department of Homeland Security said that between 800,000-900,000 people would attend Trump’s swearing-in ceremony and the ensuing parade, while tight security measures have put in place and more than 28,000 law enforcement and military personnel were deployed for the presidential inauguration in Washington.

Inauguration events started early Thursday, with a celebration at the Lincoln Memorial featuring musical performances. Trump and Vice President-elect Mike Pence later attended a wreath-laying ceremony at Arlington National Cemetery, where more than 400,000 military veterans and family members are buried. On Thursday evening, Trump, Pence and other officials attended a candlelight dinner with campaign donors.

On Friday, Trump and his family will attend a worship service in the morning before heading to the White House to have coffee with outgoing President Barack Obama and his wife, Michelle.

The outgoing and incoming presidents will then ride together from the White House down Pennsylvania Avenue to the Capitol for the inauguration ceremony.

At the Capitol, Trump and Pence will each take their oath of office at noon. Top U.S. officials and former leaders will attend the oath-taking ceremony.

Pence will be sworn in as vice president by Supreme Court Justice Clarence Thomas, while Trump will by sworn in as president by Supreme Court Chief Justice John Roberts.

After the ceremony, Congress will host a luncheon in the Capitol. Then, Trump will participate in the presidential procession and inaugural parade on Pennsylvania Avenue.

Friday night, Trump will attend three official inaugural balls, a tradition that dates back to 1809. Two balls will be held at the Walter E. Washington Convention Center, and the third, the Salute to Our Armed Services Ball, will take place at the National Building Museum.