President John Adams was already in the last year of what would be his only term as president when, on Nov. 1, 1800, he moved into the White House (though at the time, it was known as the President's House -- its White House nickname wouldn't be made official for a century).
Truth be told, it wasn't quiiiiite finished when he moved in, even though work had been proceeding since 1792. (We guess some things never change in D.C. politics or in home improvement, eh?) It looked done from the outside, but interior detailing needed two years more of work. Only six rooms were livable, compared with the 132 rooms now in use.
The White House that we know now wasn't the original plan, according to the White House Historical Association: The designer of the city's layout, the legendary Pierre L'Enfant, planned a "grand palace four times larger than the house that was built. But he was fired for being uncooperative.