- "If we are truly created equal, then surely the love we commit to one another must be equal as well," the president said. You can read the full text of the speech here.
The inauguration coincided with America's commemoration of slain black civil rights leader Martin Luther King Junior.
- Myrlie Evers-Williams, widow of civil rights activist Medgar Evers, delivered the inaugural invocation. She was the first woman to do so, and this 1963 photo of her attending her husband's funeral was shared on social media.
- This picture of Abraham Lincoln's handwritten inaugural address was also quick to be shared on Twitter.
- Crowds gathered in Washington to listen to Mr Obama's address.
- Those who couldn't be in Washington watched from their homes as the parade began.
- The inauguration festivities are even being followed from space. Canadian astronaut Chris Hadfield, who is currently living in space aboard the ISS, tweeted this photo showing Washington on Saturday night (local time).
- Back in Earth on the streets of Washington today, cheering crowds gathered to catch a glimpse of the president.