WASHINGTON — The National Museum of African American History and Culture won’t open its doors until 2016, but construction work on the building is nearly finished.

“It’s about 75 percent complete,” says Derek Ross, chief of construction for the Smithsonian.

“The outer metal facade, we’re 50 percent done with that,” he explains.

Construction began in February 2012. Cranes are now positioned around the site as workers put the finishing touches on the building.

“The folks that work for the museum are very excited about seeing the facade going up. That’s a big milestone,” Ross says.

The 400,000-square-foot museum sits on a five-acre piece of land between the Washington Monument and the National Museum of American History.

Building the museum is a major $500 million project.