MOUNT VERNON, VA (AP)- It was one of the few things George Washington wanted to do but never got around to: build a library to hold his official and personal papers. On Thursday, more than 200 years after Washington wrote of the idea, dignitaries broke ground at his Mount Vernon estate on a $47 million presidential library of sorts that they hope will evolve into a “think tank” promoting scholarship about one of the nation’s Founding Fathers. The estate hopes the library will be a home to a centralized collection of Washington’s his papers. The president wrote in a 1797 letter — two years before his death — about a library, saying his papers were “voluminous and may be interesting.” Defense Secretary Robert Gates said at Thursday’s ceremonies that