The National Army Museum at Waiouru is being updated with a new exhibition gallery and an i-SITE, and larger gift shop.
The facilities are part of the new entryway for the museum on State Highway 1.
The project will cost $2.5 million.
Matamata company Stanley Construction is the main contractor and expects to complete construction by the end of June.
The short build time was possible because a large amount of construction was pre-fabricated in the company's Matamata factory.