Although the president has his own dining room next to the Oval Office, the West Wing ground floor contains a restaurant run by the US Navy and therefore referred to in military terms as a "mess hall." This encompasses the Ward Room—a navy term that refers to an officers' dining room.
The 2006 renovations to the ground floor of the West Wing included moving the Mess Hall counter window.
Visitors in the Navy Mess in 2006 (Ronniec103)
Visitors in the Navy Mess in 2006 (Britgirl26)
Visitors outside the mess hall in 2006 (Britgirl26)
Homeland Security Director Tom Ridge meeting with Canadian Deputy Prime Minister John Manley in 2002 (White House - Tina Hager)
Old Mess Hall counter in 2002
Mess Hall dining room, circa 2001
President Bush in the Mess in 2001 (White House)
Stairs leading to the Mess (left) and Situation Room (right)
Old Mess Hall counter, circa 2001 (White House)
The Kennedys celebrating an occasion in the Mess Hall in 1963 (NARA - Kennedy Library)
The Mess Hall in 1961, looking southwest (Kennedy Library - Robert Knudsen)
The Mess Hall in 1961, looking northwest (Kennedy Library - Robert Knudsen)
The Mess Hall in 1961, looking northeast (Kennedy Library - Robert Knudsen)