Boston Nature Center is an extraordinary urban wildlife sanctuary located on a 66-acre portion of the long abandoned Boston State Hospital grounds. Halvorson Design prepared an award-winning master plan to guide Massachusetts Audubon Society's development and stewardship. Several designs conforming to the sustainable principles of the master plan followed. These include a fully accessible trail system and the grounds of the George White Environmental Center, a joint Audubon-City of Boston project that was Boston's first municipal green building.