Kevin Walsh of Forgotten New York reports:
This castle redoubt at 2744 Kingsbridge Terrace guarded the realm against invading Riverdalians and the despised Norwooders. Boiling chicken fat was poured through the quatrefoil'd buttresses at any invader who chanced to mount a frontal assault. The castle was erected in 1914.
The AIA Guide to NYC weighs in: Close by the vast veterans' hospital [at 130 W. Kingsbridge Road] is this tiny monument, a stucco castle with numerous gables, balconies, crenellated turrets, a weathervane, a TV antenna, and a tunnel reputedly leading from the "dungeon" to the street.
A shooting location featured in The Wanderers (1979)!