For information on setting up a White House tour or the logistics (what you can’t bring on the tour etc.)

The tour itself lasts about 20 - 45 minutes.

You enter the Executive Mansion from East Executive Avenue (between the WH and the Treasury Building). You're hurried through the East Wing (the First Lady's offices) and down an enclosed corridor into the basement of the mansion itself. You're allowed to peek inside the Library, the Vermeil Room, the cabinets housing the china collection, and the Diplomatic Reception Room (The Map Room, unfortunately, is just another room and looks nothing like its namesake).

Then you head upstairs to see the spacious East Room and the "colored rooms" - the Red Room, the Blue Room, the Green Room, and the Gold State Dining Room, before being shown the Pennsylvania Avenue exit (the one made famous by CJ Cregg in the series finale of "The West Wing").

The line outside is the longest part of the tour - the walk-through takes 20 – 45 minutes at most, since there's nothing to read and no narration (although there are Secret Service guards who'll shout at you if you try to touch the furniture or tapestries).

A West Wing Tour is available if you know somebody on the White House staff.  The staff member will escort you through a number of offices in the West Wing.  The highlights are the Situation Room (only the outside of it), Press Briefing Room, Rose Garden, West Wing Lobby, Cabinet Room, Roosevelt Room and the Oval Office. 

Some historical data about the White House 

Official White House Website