At the time, the northern portion of the park contained the Barclay mansion, a brick building measuring , while the southern portion contained three unidentified structures. A corps of engineers was hired to draw plans for the new park. The city acquired  in October 1913, and shortly afterward, the Board of Estimate renamed the park for mayor William Jay Gaynor.
The northern section of the park at that time featured a brick mansion called Barclay's house, measuring , while the southern area consisted of three unknown structures. Engineers were hired to design the new park layout. The city acquired  in October 1913, and shortly after, the Board of Estimate renamed the park in honor of Mayor William Jay Gaynor.