The events that lead to the chilling climax on a Berlin trestle in Steven Spielberg’s “Bridge of Spies” — the solemn exchange of captives between the United States and the Soviet Union — were ignited in real life at a nondescript Automat on 38th Street just west of Broadway in Manhattan.

What to other cafeteria patrons must have looked like an inconspicuous exchange of holiday gifts on Christmas Eve 1944 would produce another profound, if largely forgotten, consequence in the annals of Cold War espionage.

Julius Rosenberg was waiting at a table when Aleksandr Feklisov arrived. Both men placed their packages on a windowsill. Feklisov’s contained an Omega stainless steel watch for Rosenberg, a crocodile handbag for his wife, Ethel, and a teddy bear for their only son at the time, Michael.

The other box, the one that Rosenberg eagerly brought with him, weighed a hefty 15 pounds, and Feklisov prudently waited until he returned to the Russian Consulate before opening it.