WASHINGTON -- Landmark D.C. restaurant Ben's Chili Bowl celebrated its 55th anniversary Thursday with a mayoral proclamation, a congratulatory letter from President Obama and a visit from everyone's favorite TV dad.

Bill Cosby, Ben's most famous fan, arrived to cheers Thursday morning. Speaking before a crowd spilling over into U Street, Cosby eschewed the spotlight to honor instead the restaurant's longtime employees.

The Washington Post notes that Cosby isn't the only celebrity to enjoy a half-smoke at Ben's over the years:

The range of A-listers who have stopped by Ben’s is impressive. Actors Denzel Washington and Chris Tucker, the singer Bono and former French president Nicolas Sarkozy have all made appearances. In the early days, according to Ben’s, guests included Duke Ellington, Ella Fitzgerald, Miles Davis and even Martin Luther King Jr.

Cosby has been a longtime supporter of the restaurant, which famously hangs a sign stating that only one customer eats free at Ben's -- Bill Cosby (the sign was later updated to include the Obama family on the gratis list).

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In honor of Ben's 55th birthday, President and Michelle Obama sent a note saying that the family will return to the restaurant soon; President Obama chowed down on a chili half-smoke and cheese fries during a 2009 visit, just days before his first inauguration.

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D.C. Mayor Vincent Gray proclaimed Thursday Ben's Chili Bowl Day in the nation's capital.

A neighborhood institution since 1958, Ben's Chili Bowl was "one of the few businesses that remained opened through the [1968] riots" that followed the death of Martin Luther King, Jr.

The 55th anniversary celebration comes just as the city begins commemorating the 50th anniversary of the 1963 March on Washington with a packed schedule of events.

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  • U.S. civil rights leader Martin Luther KIng (C) waves to supporters from the steps of the Lincoln Memorial on August 28, 1963 on the Mall in Washington D.C. (Washington Monument in background) during the 'March on Washington'. (/AFP/Getty Images)

  • More than 200,000 civil rights militants gather on Aug. 28, 1963 on the National Mall in Washington D.C. during the 'March on Washington'. (AFP/AFP/Getty Images)

  • In this Aug. 28, 1963 file photo, President John F. Kennedy stands with a group of leaders of the March on Washington at the White House. From second left are Whitney Young, National Urban League; Dr. Martin Luther King, Christian Leadership Conference; John Lewis, Student Non-violent Coordinating Committee, partially obscured; Rabbi Joachim Prinz, American Jewish Congress; Dr. Eugene P. Donnaly, National Council of Churches; A. Philip Randolph, AFL-CIO vice president; Kennedy; Walter Reuther, United Auto Workers; Vice President Lyndon B. Johnson, partially obscured, and Roy Wilkins, NAACP. (AP Photo/File)

  • This August 28, 1963 publicity photo provided by PBS shows activists during The March on Washington in Washington, D.C. -- from the film,"Makers: Women Who Make America."(AP Photo/PBS, Courtesy Leonard Freed, Magnum Photos)

  • FILE - In this Aug. 28, 1963 file photo, the top of the Washington Monument and part of a U.S. flag are reflected in the sunglasses of Austin Clinton Brown, 9, of Gainesville, Ga., as he poses at the Capitol where he joined others in the March on Washington. (AP Photo/File)

  • U.S. civil rights leader Martin Luther KIng (3rd from L) walks with supporters during the Aug. 28, 1963 "March on Washington." (AFP/Getty Images)

  • In this Aug. 28, 1963 file photo, The Rev. Martin Luther King Jr. waves to the crowd at the Lincoln Memorial for his "I Have a Dream" speech during the March on Washington. The march was organized to support proposed civil rights legislation and end segregation. (AP Photo/File)

  • In this Aug. 28, 1963 file photo, Dorothy Height, right, National President of the National Council of Negro Women and Director of the center for Racial Justice of the national YWCA, listens as the Rev. Dr. Martin Luther King Jr., gestures during his "I Have a Dream" speech (AP Photo, File)