A wistful moment for President Barack Obama came shortly after his public swearing-in ceremony.
As he began walking off the inaugural platform to go into the U.S. Capitol for the traditional luncheon with lawmakers and other dignitaries, Obama stopped and turned around to look at the scene on the National Mall, filled with hundreds of thousands of people who braved chilly weather to be part of the day.
"I want to take a look, one more time," he said. "I'm not going to see this again."
In a nod to their increasing political clout, three Latinos played important roles in Barack Obama's public inauguration ceremony.
First, Supreme Court Justice Sonia Sotomayor administered the oath of office to Vice President Joe Biden. Nominated by Obama, Sotomayor is the first Latina justice.
Next, Richard Blanco delivered the inaugural poem, "One Today." He's the first Hispanic and the first openly gay person to serve in the role. At 44, he's also the youngest inaugural poet.
Finally, the Rev. Luis Leon, rector of St. John's Episcopal Church near the White House, delivered the closing prayer. Obama attended a worship service at the church before heading to the Capitol.
Latinos voted 7-to-1 for Obama in November's elections.
Plenty of celebrities were on hand for Barack Obama's second inauguration.
Beyonce belted out an impressive rendition of the national anthem and then returned to her spot on the inaugural platform with her husband, Jay-Z.
James Taylor sang "America the Beautiful" and Kelly Clarkson followed with "My Country `Tis of Thee."
Other celebs spotted: Katy Perry and John Mayer, who sat side-by-side, as well as actress Eva Longoria and former Boston Celtics great Bill Russell.
Not everyone was waving an American flag and cheering "Obama" at the inaugural ceremonies on Monday.
John Diamond of Arlington, Va., handed out flyers inviting people to a "dis-inauguration ball" later in the day.
"Not my president," said his flyer, with the classic Obama "O" logo part of the word "not."
Diamond, who didn't vote in this election, said he wants to encourage peace and nonviolence.
Other voices of dissent could be heard during the president's swearing-in ceremony. Even during prayers, a steady stream of "What about the babies?" wafted from the southwest of the U.S. Capitol.
Despite the chilly weather for the inauguration parade, Bobak Ferdowsi was not permitted to keep warm with a hat as he rode with the NASA float holding a model of the Mars Curiosity rover.
That's because Ferdowsi, a flight controller at NASA's Jet Propulsion Lab in Pasadena, became famous during the 2011 Mars landing for his hair, specifically his Mohawk - which doesn't fit with the 1960s NASA white shirt and pocket protector stereotype.
He became an Internet sensation, especially among the geek set, as "Mohawk Guy."
Even President Barack Obama complimented him on his hair, joking about getting one himself.
So, as Ferdowsi prepped for his first time in a parade on Monday - let alone an inaugural parade - he had a special new version of the Mohawk. This haircut had an old NASA logo - the initials for the space agency spelled out like a worm - carved in on one side near an ear and the lab's JPL logo on the other.
He was resigned to having cold ears, saying: "I don't think they'll let me wear a hat."
It didn't all go off without a hitch.
Some folks bailed on their inaugural plans when the trek to the National Mall became too long.
Cheryl Tate, 52, of Flint, Mich., and her friend Karen Pugh, 43, gave up after a long walk from RFK stadium, and went back there to sit on their tour bus, waiting for the rest of their group. While the inauguration parade continued Monday evening, they were headed back to Michigan, a 10-hour drive away. "We didn't see anything, unfortunately," Tate said, adding that others on their tour bus had been luckier.
Near the Washington Monument, people milled through the crowd of thousands to get a glimpse of the inauguration - only to find that the Jumbotron was cutting in and out and they couldn't hear the speakers. Some booed.
Moses Ashford of Columbia, S.C., didn't have regrets. "I'm happy. I'm smiling, and I see smiles on many of the people here."
A first, of sorts, at this inaugural.
For the first time in more than three decades, there was neither a Clinton nor a Bush on either the departing or the incoming presidential ticket. Since 1981, every year until now has seen someone from one of the two famous political families front-and-center on the inaugural platform.
In 1981 and 1985, it was George H.W. Bush as vice president to Ronald Reagan, followed four years later by Bush as president. In 1993, with Bush looking on, Bill Clinton took the oath as president and again four years later in 1997. Then, a departing Clinton took to the inaugural platform in 2001 as George W. Bush was sworn in. Bush had a second inauguration in 2005 and then witnessed the inauguration four years later, in 2009, of Barack Obama.
While Bill Clinton may not have been in the front row during Obama's second inaugural on Monday, Clinton and his wife, Secretary of State Hillary Rodham Clinton, did join lawmakers and other dignitaries on the inaugural platform. Former President Jimmy Carter and his wife, Rosalynn, also attended the ceremonies at the Capitol's west front.
Associated Press writers Nancy Benac, Seth Borenstein, Alan Fram, Philip Elliott, Mesfin Fekadu, Kevin Freking, Jessica Gresko and Stacy A. Anderson contributed to this report.