The Children's Museum of Denver has announced plans for an expansion project that will more than double its exhibit and program space.

The $15.8 million campaign will add two wings on to the current building and also includes plans for an outdoor play area. 

Officials say that attendance at the museum, which opened in 1973, has grown nearly 75 percent since 2003.

Museum president Mike Yankovich says more space is needed in order to better serve attendees.

"Children’s museums are the fastest growing museum segment in the country right now," Yankovich says. "It really does become an investment in the future of their community."

The strategic planning effort began seven years ago. During planning, museum officials visited children's museums that have recently expanded in other cities like Boston and Indianapolis. 

"It wasn’t just about getting bigger, it was about getting better," Yankovich says. "There’s a real emphasis on understanding how children learn and the essential for hands-on, authentic, relevant experiences that organizations like children’s museums offer."

The expansion will make room for eight new interactive exhibits, including an art gallery, a teaching kitchen and an urban water system laboratory. The Colorado-themed outdoor site will include creeks, a cave, forts and a zipline.

The project will also add parking space and other guest amenities.

The museum has so far raised $13.3 million, including private funds from foundations and individuals and a $150,000 grant from the Institute of Museum and Library Services.

The new Children's Museum of Denver at Marsico Campus will stretch across nine acres and is expected to open by winter 2015. Construction begins this week.