Less than 24 hours after Donald Trump's stunning victory in the United States presidential election, transition offices for the President-elect have opened blocks away from the White House.

Late Wednesday afternoon, the General Services Administration issued the formal ruling that Donald Trump is the "likely winner," allowing the presidential transition to begin and Trump's team to move into an office space at the GSA building.

Trump's transition team will hold meetings with federal agencies and pick prospective cabinet members at the office on F Street NW.

The Heritage Foundation, a conservative policy think-tank, is helping with the transition.

"The new team needs to be able to walk in the door and be ready to go in case there's a 9/11 on January 21st," said Jim Carafano, vice president for the Kathryn and Shelby Cullom Davis Institute for National Security and Foreign Policy at The Heritage Foundation.

Inauguration planning is also in full speed.

The inaugural platform at the U.S. Capitol Building is already taking shape and a committee is sending invites to prospective performers.

Missouri State University's choir is one group that has been chosen to perform.

The 58th Presidential Inauguration will be similar to the inaugurations of past presidents, aside from some festivities that will be custom-tailored for Trump.

"We will work directly with the Presidential Inauguration Committee, which will be set up by President-elect Trump. Those are his direct representatives. They'll define for us their requirements for balls, galas and for ceremonies, other than the actual swearing in that will happen on the 20th of January," said Lt. Col. Jeff Davis, with the Joint Task Force-National Capital Region.

While D.C. overwhelmingly voted for Hillary Clinton, Mayor Muriel Bowser said the District will put out the welcome mat for Trump's inauguration.

"We have been through this many times -- our home, of course, every four years. Our Homeland Security division with the Metropolitan Police Department will work with our federal partners in preparation for the inauguration," Bowser said.