Take a look at the ten largest homes in the United States that were built before 1950. Nine of these homes are open to the public and get millions of visitors every year but the one home on the list that is actually owned by the public is not open for tours anymore. Every one of these homes is a great place to visit. Pictured is The Breakers in Newport, Rhode Island. The home has 70 rooms covering 65,000 square feet, and it's only number five!
Link
(image credit: Wikipedia user upstateNYer)
From the Upcoming ueue, submitted by hemlcok.
http://www.whitehouse.gov/about/tours-and-events
You have to give advance notice, but the first sentence says it best, "Public tours of the White House are available."
It eventually crashed the browser.