An hourlong documentary, “Community Cornerstone: African American Communities in Montgomery County, Maryland,” will be premiered at 7:30 p.m. Monday at the Universities at Shady Grove, 9630 Gudelsky Drive, Rockville.

Between the Civil War and the Civil Rights movement, 40 black churches were built in the county. There, generations of families created their own spiritual, social and educational opportunities.

The video portrays elderly members of five historic churches who reminisce about how the community developed and discuss life during segregation. The choirs associated with each of the featured churches are highlighted.

The free showing, hosted by nonprofit Heritage Montgomery, will be preceded by a reception at 6:30 p.m.

Seating is limited. For reservations, email heritagemontgomery@gmail.com. More information is at heritagemontgomery.org.