Southern New York
Great places with free admission and / or programs 

Alley Pond Environmental Center free admission; charge for some programs 
American Illustration, Museum of free admission and tours, including groups  
Brooklyn Botanical Garden free on Tuesdays, free for seniors on Fridays; free for School Groups; fee charged for parking & programs  
Butler Preserve free admission  
Castle Gallery free admission, tours & programs, incl. groups  
Clay Pit Ponds Preserve free admission & programs, incl. groups  
Eugene & Agnes Meyer Preserve free admission  
Harbor Defense Museum free admission  
International Ladies Garment Workers Union free tour for GROUPS ONLY  
Jamaica Bay Wildlife Refuge free admission  
John F. Kennedy International Airport free tour for GROUPS ONLY  
Judaica Museum free admission; fee charged for group tours & school programs  
Lenoir Preserve free admission, donactions appreciated; fee for programs  
L.I. Wildlife Refuge Complex free admission to Wertheim Refuge  
Marine Nature Study Area free admission & school tours; fee for some programs  
Marshlands Conservancy free admission; fee for programs  
Muscoot Farm Complex free admission, incl. groups; may be parking fee  
Muttontown Preserve free admission; fee for programs  
National Museum of the American Indian free admission, incl. groups  
NYS Unified Court System Tours free tours for groups only  
New York Stock Exchange free tour, incl. groups  
Polish American Museum free admission  
Rye Nature Center free admission; fee for programs  
Teatown Lake Reservation free admission to trails, donations appreciated; fee for programs  
Trailside Nature Museum -- Pound Ridge free admission - $2.00 donation appreciated, fee for some programs; parking fee  
United States Postal Service free tour for groups  
Washington's Headquarters free admission & programs