This is the 1912 All Soul's Chapel, located at Poland Spring Preservation Park. I posted a photo of it back in January (chapel). The park is also where the original spring house for Poland Spring water is located (picture of that is here: source )
Also located on the grounds is the Maine State Building, which you can see on the right in this photo. It was built for the 1893 Chicago Worlds Fair and moved here.
The top of the Maine State Building: