The brief observance took place Monday at HUD headquarters and was administered by Chief Judge Richard W. Roberts of the U.S. District Court for the District of Columbia.

President Barack Obama chose Castro to replace Shaun Donovan as housing secretary. Obama picked Donovan to become White House budget chief.

Obama called Castro "a champion for safe, affordable housing and strong, sustainable neighborhoods."

Castro takes over an agency with 8,000 employees and a $46 billion annual budget.

Castro got national exposure two years ago when Obama selected him as keynote speaker at the 2012 Democratic National Convention.