Oval Office

The Oval Office is, perhaps, the most famous room in the White House. (After all, it is where the president spends a lot of time.) It didn't officially become the president's main office until 1909, though. According to the White House Historical Association, President William Howard Taft decided to enlist the help of an architect to turn the then-makeshift West Wing office into a room for longterm use. President Taft asked multiple architects throw their hats into the ring for this opportunity — and Nathan C. Wyeth came out the winner. He planned and designed the entire extension of the West Wing of the White House, and what is now the Oval Office. He based some of his designs off of the Blue Room, which happened to have rounded walls. Hence, the Oval Office was created with a similar oval shape.