Van Cortlandt Manor at the sourthern end of the Parade Ground. Nothing to do with the New Deal, but it's a historic house and a park landmark. The Van Cortlandt family bought the land in 1710, built the house in 1748, and lived in it until 1888, when the City took possession. In 1776 George Washington had his headquarters here while his troops camped on the adjoining Parade Ground.

References:

1. Van Cortlandt Mansion and Museum, New York City Parks Department website.
2. Ultan, Lloyd, and Shelley Olson, The Bronx: The Ultimate Guide to New York City's Beautiful Borough, Rutgers University Press (2015), pp.31-41.