No it’s not somewhere a hobbit might live. It’s the former main powder mill building.

According to Wikipedia:

The Orange Mill Historic District…takes its name from the old gunpowder mill complex, built by Asa Taylor in 1816 and operated by the Laflin & Rand Powder Company after 1869. It is located along the unnamed Orange Lake outlet brook which flows through the park just above its outlet at Quassaick Creek.

While it primarily produced powder for local residents’ use in hunting and shooting sports, during the Civil War the Union Army procured some higher quality material. In the years before that conflict, local historian Edward Ruttenber claimed the mills were “the most complete and extensive works in the country” when they were under the ownership of a man named Daniel Rodgers.

After production stopped in the early 20th century, developers began building on houses on some of the property. Col. Frederic Adrian Delano (1863–1953), uncle of future President Franklin Delano Roosevelt, purchased the remaining land, which included the core of the manufacturing operation, for use as a public park.
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Today the historic district includes 14 of these buildings which formerly were the core of the manufacturing operation as contributing properties. It was designed to incorporate the old buildings as an essential feature, and many of the roofless stone structures still stand next to the park’s barbecue pits and picnic grounds. It is today the only remaining 19th-century gunpowder production facility in New York. It was added to the National Register of Historic Places in 1997.