Harlem is a neighborhood in upper Manhattan. Its citizens consist basically of Afro-American people, who moved to Harlem during the beginning of the 20th century and after it. Originally it was a Dutch village, founded in 1658. Poverty and crime was a beg threat in Harlem a few decades ago still, but nowadays the birthplace of jazz is alive again.
During our trip to New York we had a chance to see Harlem as well. On a tourist bus, we drove through the neighborhood and saw for example the Apollo Theater, and a subway train coming out of the tunnel. We also drove along Malcolm X Boulevard, having a good overview of the place.
P.s. You can find this impressive monument near Harlem, in Morningside Hights, as well: Grant's tomb, officially called General Grant National Memorial. It is worth the visit if you are in the neighborhood.