“The Oval Office” is the official office of the President of the United States. It is located in the White House in Washington, DC. “The Oval Office” is often used as a metonym for the President or the Presidency. For example:

• “This is an ancient conflict, and the Israeli Prime Minister is in no hurry to help the latest US President to achieve what his predecessors in the Oval Office failed to do.”—Tim Reid, “Analysis: Tried and tested tactic to wear a President down,” The Times (UK), June 15, 2009;
• “Since reaching the Oval Office last January, Mr. Obama has ordered more than 20,000 additional soldiers and marines to Afghanistan, boosting the coalition of foreign troops to more than 100,000 – or roughly the peak level deployed by the Soviet Union in its 10-year failed effort to subjugate Afghanistan.”—Paul Koring, “Dissent mounting to Obama’s Afghan strategy; U.S. President may need allies outside his own party should he decide to send massive reinforcements to Afghanistan,” The Globe and Mail, September 15, 2009, p. A16;
• “All in all, Ms. Palin emerges from “Going Rogue” as an eager player in the blame game, thoroughly ungrateful toward the McCain campaign for putting her on the national stage. As for the McCain campaign, it often feels like a desperate and cynical operation, willing to make a risky Hail Mary pass in order to try to score a tactical win, instead of making a considered judgment as to who might be genuinely qualified to sit a heartbeat away from the Oval Office.”—Michiko Kakutani, “Memoir Is Palin’s Payback to McCain Campaign,” The New York Times, November 15, 2009.