Where in Washington?

Here's this week's stumper, from the collection of Jerry McCoy:

Send the name of this building--what it would have been called then, not now--to kellyj@washpost.com. If yours is the first correct entry I receive, you'll get a postcard signed by a Washington Post Pulitzer winner.

Washington's Laura Byrd was last week's winner, correctly identifying the postcard of Meridian Hill Park, aka Malcolm X Park.