This Sunday is going to be a big day in the nation's capital. June 14 happens to be Flag Day, the anniversary of the U.S. Army's founding and President Trump's 80th birthday. It also comes just under three weeks before the United States' semiquincentennial — the overly complex word for its 250th anniversary.

At the same time, the Trump administration is hosting the first-ever professional fights on the White House's grounds, while Trump's critics will hold a concert and community events to protest his administration.

Here's a rundown of what's going down in Washington, D.C., and across the country on Sunday.

The marquee event on Sunday is the unprecedented mixed martial arts competition being held on the White House grounds. A massive, 90-foot-tall arch that's been dubbed "The Claw" and a temporary 5,000-seat arena have been built on the South Lawn of the White House for the event.

A separate viewing area on the Ellipse will allow as many as 80,000 fans to watch the matches on giant screens. The fights, which are headlined by a lightweight championship contest between Spanish-Georgian Ilia Topuria and American Justin Gaethje, will also be broadcast live on Paramount+ starting at 8 p.m. ET.

The fate of the event had been uncertain amid an ongoing legal battle stemming from a lawsuit filed by a group seeking to prevent it from happening. On Friday, a federal judge ruled that the fights can go forward as planned. There is a chance, however, that Mother Nature may interrupt the festivities. Forecasters are expecting at least some rain in Washington, D.C., on Sunday night — with some models predicting possible thunderstorms.

There are no official events specifically celebrating the president's 80th birthday at the moment. But the milestone will no doubt be a big part of Sunday's activities as his supporters and political allies offer well-wishes throughout the day. It will likely be a similar vibe as last year's military parade, which formally honored the Army's 250th anniversary but also created ample opportunity for Trump's backers to celebrate his birthday.

Trump is just the second president in history to reach the age of 80 while in office, after his predecessor Joe Biden. If he serves until the end of his second term, Trump will pass Biden to become the oldest president ever in August 2028.

At around the same time that the first fights at the White House begin, a concert celebrating the rights granted by the First Amendment of the U.S. Constitution will also be starting in New York City.

The Rise Up: Sing Out event will feature appearances and performances from a list of major stars, including Bette Midler, Julia Roberts, Patti Smith and Rufus Wainwright. It's being planned by the Committee for the First Amendment, a group that was founded in 1947 to protest the government's investigations into alleged Communist activities in Hollywood at the time. Actress and activist Jane Fonda, whose father Henry was a member of the original committee, revived the long-dormant organization last year to push back on the Trump administration's efforts to "silence critics" in the media and other institutions.

"This 90-minute concert event will celebrate the freedoms guaranteed by our First Amendment — of speech, religion, press, assembly, and protest — and the people power that both fuels these rights and is essential to guarantee them," the event's website says.

Just like they did last year, organizers with the "No Kings" movement are planning nationwide events in opposition to the Trump administration on the president's birthday. But this year's events will be very different from the mass protests that filled the streets in hundreds of cities across the country — or the two similar national days of protest that have been held since then.

This year, organizers are using the Rise Up: Sing Out concert as an "anchor" for local events centered around celebrating community, rather than protesting the president.

"Across the country, communities will gather for local watch parties to sing along, make art, share food, connect with neighbors, and take meaningful action together," the group wrote on its website.

The goal of Sunday's gatherings is to help "No Kings" move "beyond mass street mobilizations" and to start "building hyper-local infrastructure" to combat the Trump administration, organizers wrote.

There are more than 300 events planned for Sunday across the country.