Key story highlights:
The Smithsonian expects the National Capital Planning Commission to approve its South Campus master plan in June.
One of the key components of the master plan includes the rehabilitation of the campus' 1855-era castle.
The Smithsonian won't begin construction on the South Campus plan for another decade.
After years of planning, the Smithsonian Institution expects to receive final approvals from the federal agency reviewing a master plan for its 17-acre south campus as early…
