1819 7th Avenue is a huge house, built in 1900. At some point before 1944 it was divided into separate units.
Questions: who was it built for? who was the architect? has anyone of note lived there?
The 1939 directory lists Emory and Nellie Serva, so it's likely the 1940 directory has a typo (or I need to use my reading glasses...)
The 1940 street directory lists Nellie Serra as the sole resident, phone number HIghgate-2056.
The 1944 street directory lists 3 apartments, one unpublished, Mrs. Belle Johnson in one, and Marthela Willis in another.
It is parcel #21-232-8. Zillow says it was built in 1900, has 18 bedrooms and is 7049 sq. ft. It last sold in 2006 for $1,280,000.
The 1903 Sanborn map confirms it was built 1903 or earlier, and that (unsurprisingly) the boxy area on the left is a later addition.
In the 1900 Census, the street number was 1407. It was occupied by Alexander Nowell, an English coffee planter.
Between the 1910 and 1920 Census, the number changed to 1819. Both Census show owned by Birdsall McAllister, a NY-born land commissioner for Southern Pacific RR.
By 1930, it was a boarding house occupied by 27 people in 13 units.