David Conley Nelson explains building in which Heber J. Grant spoke in Frankfurt was owned by the Nazis.
David Conley Nelson, Moroni and the Swastika: Mormons in Nazi Germany (Norman, OK: University of Oklahoma Press, 2015), 217
The prophet, seer, and revelator Heber J. Grant was also an appreciated visitor when he spoke to an assembly of one thousand Mormons in front of a large swastika banner at a rented banquet hall in Frankfurt on July 8, 1937. The building belonged to the National Socialist Teacher’s League, the Nationalsozialistische Lehrerbund. Like any meeting place available for rental in Nazi Germany, it came equipped with a large national flag, this one red with a black swastika in the center of a white circle. Prudent tenants did not take down Nazi flags during this period in German history, although the German Mormons probably would not have been motivated to do so. Grant spoke of spiritual topics but encouraged the faithful to pray and be persistent in their daily work. The message was consistent with others delivered to Latter-day Saints outside of the United States during the Great Depression. Work hard, obey the law of the land, and build up the church at home rather than emigrating.