Actually, not much about it has changed since it was built as a single-family dwelling in 1871, purchased by one S.J. Lazarus for about $10,000. By the mid-1880s, as Prospect Hill's fortunes started into decline, it became a boarding house, and it seems to have shifted back to single-family use around the turn of the century. When the French Company began buying up the neighborhood in 1925, it was a hold out. In 1970 it was sold to real estate titan Harry Helmsley, no doubt to be demolished as part of his plans to build on the Tudor City parks.
Helmsley's plans, of course, failed. 337 E. 41st Street remains a single-family dwelling today and cannot be altered ‒ it's part of the Tudor City Historic District.