Downtown Durham is hot, and it's impossible to walk a block of it without wowing over a restaurant or co-working space or funky apartment that was a vacant storefront just a year or two ago. But this kind of hotness is also a process of cultural loss. Downtown boosters would be wise to catch a screening of the 1948 documentary Negro Durham Marches On, produced by the Durham Business and Professional Chain (basically a black chamber of commerce of its time). The film highlights various Hayti neighborhood businesses and organizations during a period of post-World War II prosperity, before urban renewal mowed Hayti down a decade later. Community historian Kelly Bryant hosts the free screening at 3 p.m. —Chris Vitiello