San Carlos-based Gonsalves & Stronck has finished construction on the Marine Mammal Center, a $20-million veterinary hospital.

The marine mammal center contains 39 outdoor pens and pools for animals.

The center was developed from a four-acre former missile silo bunker site located in the Marin headlands. Architects Noll & Tam and Scott Dennis Architect designed the project to incorporate sustainable elements, including radiant floor heating, natural daylighting and ventilation and native vegetation.

The underground missile silo bunkers were transformed into spaces to operate the mechanical infrastructure and pumping and filtration systems for the center. The center contains 39 outdoor pens and pools for animals.

The project also included the construction of a retail and educational center, administrative offices and a mechanical shop and locker.