Joe Biden is officially president, Kamala Harris is the country's first Madam Vice-President and Donald Trump flew off to play golf - all of that we expected.
But here's a look at those inauguration day moments you might have missed, some solemn, some emotional, but also the podium wipe guy.
Katy Perry's Firework
It was hard to find any downbeat comments after the white-clad Katy fired off her epic anthem to close out the day in front of the Washington Monument - as the Bidens stood watching from their balcony.
Although Firework as a song has drawn many interpretations, from sex to firework safety to LGBT rights, it seemed a pretty good fit here.
The exploding background didn't do any harm, but the lyrics weren't too off track either.
"Do you ever feel like a plastic bag/Drifting through the wind, wanting to start again?"
Well-known Twitch streamer hasanabi tweeted "katy perry is right, trump DID make me feel like plastic bag!"
Oh, and the song swept back into the US iTunes chart of course.
That's how it all ended but let's go back to the start...
Before Joe took over, Donald first had to leave.
Perhaps not all of the Trump administration could be called carefully choreographed, but the strains of Frank Sinatra's My Way ringing out as Air Force One swept Mr Trump out of the presidency and off to Florida is hard to fault.
Air Force One leaves Joint Base Andrews, with US President Donald Trump onboard for the final time – as the Frank Sinatra song, My Way, plays out across the air basehttps://t.co/AbQxlbyS9h pic.twitter.com/UFAH2VgJic— BBC News (World) (@BBCWorld) January 20, 2021
We can't say for sure he planned it himself and the other tunes banging out at Andrews base - like Elton John's Funeral for a Friend - were hard to parse for some.
Mr Trump's a big fan of Sinatra apparently. Though it's not reciprocated - Sinatra's daughter, Nancy, said her father loathed the then real estate mogul.
The other Trumpism drawing attention was Melania's outfit change.
It was quickly pointed out that Mrs Trump had used her flight from Andrews to Florida to quickly update her wardrobe to suit her new, post-first lady life.
Some noted her relaxed smile after touching down in Florida - an apparent contrast to her demeanour at her husband's inauguration four years ago.
And on to the inauguration ceremony...
Bernie: his mittens, his envelope, his style
The first sensation came from Vermont Senator Bernie Sanders with his sensible choices for Washington's near-freezing weather - an outdoorsy jacket with woollen mittens accoutred with a brown manila envelope.
Channelling a grumpy uncle at a February wedding or a man in an unheated waiting room, he brought new glory to the timeworn philosophy of bringing yourself and nothing else to an occasion.
The internet was quick with the Bernie memes 😭 pic.twitter.com/ymtP3YIOQA— Natasha 𓇼 (@ndelriego) January 20, 2021
It's clearly a creed that President Biden's choice for Treasury Secretary, Janet Yellen, ascribes to as she too was pictured wearing a cold-defying black parka, a face mask and black gloves. And a BYOB (bring your own blanket).
everyone is talking about Michelle Obama but turns out my fashion icon is Janet Yellen pic.twitter.com/10snrjcDpS— Adrienne Porter Felt (@__apf__) January 20, 2021
But the patterned brown wool mittens have a story of their own that is also very on brand and had some gushing. The mittens were reportedly made by schoolteacher Jen Ellis from his home state of Vermont, using repurposed wool sweaters and recycled plastic bottles.
A nod to Senator Cory Booker for one of the coldest barbs of the day.
The New Jersey Democrat got a ton of reaction for his Facebook post welcoming the inauguration no-show of the 45th president, Donald Trump, by saying the temperature was -45.
Shades of purple
The colour purple - well hues of it at least - hit the small screen in a big way.
Kamala Harris in purple, Hillary Clinton in amethyst, Michelle Obama in a plum-coloured turtleneck and trouser design.
Why purple? Well it has a long history with the suffragette movement, and has been promoted by some as an intertwining of Republican red and Democrat blue. It's a unity thing.
Lady Gaga appeared with a gold Schiaparelli gilded dove of peace brooch so large it threatened to fly her off the stage as she sang the national anthem. Suffice it to say she was on less controversial ground with an ancient symbol of love and peace than a dress made of meat (like the one she wore back in 2010).
One - in fact two - of the sweetest outfits were worn by Amara and Leela Ajagu, the four- and two-year-old great nieces of Kamala Harris. They wore their faux leopard fur coats because they wanted to be like her.
Ms Harris had worn a similar outfit in a 1970s photo with the children's grandmother (and her sister), Maya Harris.
Which brings us on the kids' father, Nikolas. He's the partner of Kamala's niece, Meena, and was also the subject of a social media trawl after an eagle-eyed screen-shotter spied a pair of jaunty Dior Air Jordan 1 sneakers on the stairs during Senator Amy Klobuchar's speech.
He did get some stick, with tongue-in-cheek praise for "making black history" and "daring to drip" at a presidential inauguration. The shoes are limited edition and could get $10,000 on resale. Meena later explained in a tweet.
When Nik was packing for DC he actually asked me whether he should bring Jordans or stick to dress shoes. I didn’t know which Js he was considering, and apparently I was in a jolly mood so I said “Do what makes you happy.” He never followed up either way. Anyway what a great day.— Meena Harris (@meenaharris) January 21, 2021
A historic fist bump
But it wasn't all fashion.
What an amazing and historic photo. pic.twitter.com/ofLGTN6Bvj— Doug Gordon (@dgordon52) January 20, 2021
Barack Obama - the country's first black president - exchanged an inauguration day fist bump with Kamala Harris.
The moment was celebrated as a historic passing of the torch between the two political trailblazers, the only black Americans in history elected to serve in the White House.
Eugene Goodman escorts the vice-president
What a wild two weeks for our country but especially for people like Capitol Police Officer Eugene Goodman.— Yashar Ali 🐘 (@yashar) January 20, 2021
On Jan 6, he put his life on the line when he lured insurrectionists away from Senators and staff.
Two weeks later, he’s escorting VPE Kamala Harris into the US Capitol pic.twitter.com/zBKzQeJ3lR
Kamala Harris also had a special security escort: Capitol Police officer Eugene Goodman.
Mr Goodman has been hailed as a hero after his actions during the storming of Capitol Hill earlier this month. Footage from inside the deadly insurrection shows the officer singlehandedly steering a mob away from the Senate chamber, while the lawmakers hid inside.
Mr Goodman accompanied Ms Harris in his new role as deputy Senate sergeant-at-arms.
She took her oath with her trademark smile about to burst through the historic moment, and as President Biden took his the emotion was also evident on his wife Jill's face.
And as the podium was handed from one storied speaker to another - from senators to longtime advisers of President Biden - one man made sure to jostle them to the side before they took the microphone, for their own protection of course.
Podium wipe guy, as he became known, disinfected the stand between each speaker and was lauded (online) as one of the unsung heroes of the day. It's never been seen before at an inauguration, it's a ritual that may well be here to stay.
Amanda Gorman for president?
And finally - we knew to expect poet Amanda Gorman in the inauguration line-up, but we did not know how much she would resonate with people around the world.
"When day comes, we ask ourselves where can we find light in this never-ending shade?" began Gorman, the country's youngest ever inaugural poet.
At today's celebration, the 22-year-old performed her poem titled "The Hill We Climb"- penned after the Capitol riots. The writer and performer became the country's first national youth poet laureate in 2017.
Today, the self-described "skinny black girl, descended from slaves... [who] can dream of becoming president" has found "herself reciting for one". But her ambitions don't end there - according to former Secretary of State Hillary Clinton, Ms Gorman has promised a future presidential run of her own.