Politico reports that Zuckerberg quietly purchased a 15,000 square-foot mansion in Washington, D.C. for $23 million in cash, making him the latest billionaire tech C.E.O. to purchase a pied-a-terre in the Capitol. It’s the third-highest real estate transaction in D.C. history, and was so secretive that “soon after the deal went through in early March, images of the house became pixelated on Google Maps.”