This week, President Obama and three former presidents are hanging out at the presidential library of a fourth president. The reason? 2014 marks the 50th anniversary of the Civil Rights Act, and political leaders from all over the country are descending upon the LBJ Presidential Library in Austin to assess how things have changed -- and how they haven't. Here's a quick guide to who will be there and what you should know.

President Lyndon B. Johnson on July 2, 1964, signs the Civil Rights Act in the East Room of the White House. Standing from left, Sen. Everett Dirksen (R-Ill.), Rep. Clarence Brown (R-Ohio), Sen. Hubert Humphrey (D-Minn.), Rep. Charles Halleck (R-Ind.), Rep. William McCullough (R-Ohio) and Rep. Emanuel Celler (D-N.Y.). (Associated Press)

First things first, which presidents will be there?

President Obama and former presidents George W. Bush, Bill Clinton and Jimmy Carter will all be speaking at the summit. To add another president to the mix -- President George H.W. Bush is an honorary co-chair.

University of Texas at Austin political scientist Bruce Buchanan told the Houston Chronicle, "It's a milestone celebration on a very important topic -- the effort to achieve equality -- and that's why it matters. That's why those presidents are here. Lyndon Johnson, of course, is the central figure in making the laws comport with our values, and these presidents are here to express their respect for that."

Carter is speaking Tuesday at 6 p.m. Central time. Clinton will speak at 6 p.m. Wednesday. Obama will give the event's keynote address at 11:30 a.m. Thursday and Bush will be speaking at 5:30 that evening.

When Obama's attendance was announced, LBJ Library Director Mark K. Updegrove said, “We are truly honored to host President Obama as the keynote speaker at the LBJ Presidential Library’s Civil Rights Summit in April. The world has evolved considerably in the half century that has passed since the signing of the 1964 Civil Rights Act. As our first African American president, Barack Obama is the fulfillment of the promise of the Civil Rights legislation delivered by President Johnson and a bipartisan Congress.”

Because Obama and the past presidents will be present, there will also be intense security measures at the event. Multiple police departments will be providing services, and the Secret Service will be out in full force.

“In the end, all of us are supplementing the Secret Service,” Austin Police Department Sgt. Jeff Crawford told the University of Texas campus newspaper, the Daily Texan. “It’s kind of their show. They make the majority of the calls, but we have a good working relationship with them and they work really well with us.”

Who else is speaking? Anyone interesting?

When you manage to get four presidents under one roof, it's not hard to bring in the rest of the troops: 46 people will be speaking at the event. Here are some speakers worth paying attention to:

  • At 12:35 p.m. Tuesday, high-profile lawyers David Boies and Theodore B. Olson will discuss how gay rights fits into a discussion of civil rights. Boies and Olson are from different political parties, but teamed up to fight California's Proposition 8 in the Supreme Court. They won and are trying to get involved with the next big same-sex marriage legal battles in Utah and Oklahoma.
  • At 1:40 p.m. Tuesday, former Mississippi governor Haley Barbour and San Antonio Mayor Julián Castro will discuss immigration policy in the 21st century. The conversation will be moderated by Brian Sweany, an executive editor at Texas Monthly.
  • At 12:35 p.m. Wednesday, there will be a panel on LBJ and Martin Luther King, Jr. Civil rights historian Taylor Branch, Joseph A. Califano Jr. -- a special assistant to LBJ -- and former U.S. ambassador to the United Nations and congressman Andrew Young (D-Ga.) will take part in the discussion, moderated by journalist Todd Purdum.
  • At 1:40 p.m. Wednesday, there will be a panel on sports and civil rights with Cleveland Browns running back Jim Brown and Boston Celtics center Bill Russell.
  • At 2:40 p.m. Wednesday, civil rights leaders who were there at the beginning will reflect on the movement's history. Rep. John Lewis (D-Ga.), former NAACP chair Julian Bond and Young will speak, and Lonnie J. Burch III, founding director of the National Museum of African American History and Culture will moderate.
  • On Thursday, tennis player Billie Jean King and Bloomin' Brands chief executive Elizabeth A. Smith will discuss the glass ceiling. Editor and media empire builder Tina Brown will moderate.

Here's a schedule for the whole event.

Why is it being held at the LBJ Library?

Because it's the 50th anniversary of the signing of the Civil Rights Act by President Lyndon B. Johnson.

It's also a ripe time to discuss what civil rights means today. The Voting Rights Act hasn't been reauthorized since 2006. Many Supreme Court decisions in the past few years have reversed many initiatives started in the 20th century to help minorities, while other cases -- especially in regards to gay rights -- have made social equality more robust. As much as the 50th anniversary and the setting up the summit frame the issue as a backward glance at a movement, these issues are very much still at the center of American politics, as the range of the panels and speakers show.

Although much of the discussion of civil rights will discuss the 21st century and the future, it's clear that many historians and employees at the LBJ Presidential Library hope the event will bring renewed attention to Johnson -- and perhaps give his legacy more to work with than his record on Vietnam.

The fact that the summit is taking place in Texas has definitely helped push the event to tackle a broader range of issues than the first Civil Rights Act addressed. "Certainly in this state, the status of Hispanics is a major feature," LBJ School of Public Affairs Dean Robert Hutchings told the local Austin public radio station. "There are other civil rights aspects too that really weren't major issues 50 years ago, but are now. And certainly gay rights are one of them, disability rights is another. It's a time to reflect on all these issues."

Where can I watch the events?

If you were one of the lucky people to snag the 967 seats in the Lady Bird Johnson Auditorium, great job! You get to watch it live. If you're not in Austin -- or are one of the nearly 9,000 unlucky University of Texas students who didn't manage to get a ticket -- here's the livestream.

GALLERY: When presidents get together, in images