The Prelinger Archives are something special. In addition to dozens of bizarre educational films from the mid-twentieth century, they've also got some great vintage films about New York City.
Go "Around the World" in the 1940s and never leave New York, aka "Baghdad on the subway"--from the Jewish Lower East Side to a Puerto Rican neighborhood to an Italian bocce court and kitchen, it's quite a trip.
Hop on the Third Avenue El in the 1950s:
Then fast forward to the 1960s and spend a Sunday in Greenwich Village:
See the whole list of films here.