Meet San Antonio Mayor Julian Castro, President Obama's nominee to become the nation's housing secretary. The 39 year-old will replace Shaun Donovan, current secretary of the Department of Housing and Urban Development. Castro made history when Obama chose him to deliver the keynote address at the 2012 Democratic National Convention, becoming the first Latino to do so. Castro is currently serving his third term as mayor of San Antonio. He's been called a potential Democratic vice presidential candidate in 2016 -- and has even been referred to as "the next Obama."