Who or what was Levas Politopulos?  I already found the listings at
http://home.nyc.rr.com/jkn/nysonglines/34st.htm and
http://home.nyc.rr.com/jkn/nysonglines/9av.htm via Google search, but
found them to contain no explanatory information.

Hello houli-ga

I am not a Google Answerer. Maybe this will help them, though.

Levas and Politopulos (also spelt Politopoulos) are each family names.
Some buildings sport the name of the person or persons who erected the building.
Without their first name, and without any local knowledge of the
neighbourhood, it will be difficult for a search to bring up anything.

Sincerely
fairesavoir-ga