"The Fall of the City" is an OTR drama written by Archibald MacLeish (1892-1982) as an episode of The Columbia Workshop series. The drama focuses on the collapse of a city under an unnamed dictator, a commentary on the growing fascism in Germany and Italy just before the start of World War II. Featuring Orson Welles, "The Fall of the City" is often cited as the best example of the artistic potential of radio broadcasting in terms of both stylistic innovation and social power.
"The Fall of the City" is significant as the first American verse play written for radio and for the idiomatic use of radio and its resources. Both are distinguishing steps toward establishing the idea of radio art as poetic, sound-based drama.
Written in the form of a radio broadcast, "The Fall of the City" was the first American verse play for radio. Archibald MacLeish (1892-1982), Pulitzer Prize-winning poet, writer, and Librarian of Congress, submitted his script in response to a call from the producers of The Columbia Workshop radio series for experimental work. Script available here.
MacLeish claimed two uncontested conquests of one nation by another as inspiration for his radio drama. The first was the 1521 conquest without resistance of the Aztec city Tenochtitlan (tã-nóch-tët-län, now Mexico City) by Hernán Cortéz of Spain. MacLeish visited Tenochtitlan in 1929, where he may have learned the Aztec legend of a woman who returned from the dead to prophesize the fall of the city just days before its conquest.  The second source of inspiration was Nazi Germany's uncontested annexation of Austria prior to the start of World War II.
"The Fall of the City," MacLeish said in later interviews, was not about the conqueror, but rather about the way people lose or sustain the burden of freedom.
"The Fall of the City" was first broadcast by the Columbia Broadcast System (CBS) as part of The Columbia Workshop radio series (1936-1943 and 1946-1947) on Sunday, 11 April 1937, 7:00-7:30 PM EST (episode 35). Orson Welles and Burgess Meredith starred, Irving Reis directed. The 30-minute broadcast originated from the Seventh Regiment Armory, New York, a location large enough to accommodate the hundreds of extra actors required for the crowd scenes. The cast included . . .
House Jameson (Studio director)
Orson Welles (Announcer)
Adelaide Klein (Dead Woman)
Carleton Young (1st Messenger; Later played the lead, Philip Gault, in the OTR crime series The Whisperer)
Burgess Meredith (Orator)
Dwight Weist (2nd Messenger)
Edgar Stehli (Priest)
William Pringle (General)
Guy Repp, Brandon Peters, Karl Swenson, Dan Davies, Kenneth Delmar (Antiphonal Chorus)
A second broadcast, 28 September 1939 (episode 156), originated in the Hollywood Bowl, Los Angeles, California. The cast featured Myron McCormick, Burgess Meredith, Dorothy Meredith, Ted Osborne, and Earl Ross.
Reception of "The Fall of the City" was positive. The writing, use of sound effects, and radio production techniques were all noted as opening a new era for radio drama. 
The Columbia Workshop commissioned MacLeish to write another radio drama, "Air Raid," again in the form of a radio broadcast, and broadcast both the dress rehearsal on 26 October 1938 and the final production on 27 October 1938 (episode 110, starring Aline McMahon and Orson Welles). Script available here.
 Bernard A. Drabeck and Helen E. Ellis, eds. Archibald MacLeish: Reflections. (Amherst, The University of Massachusetts Press, 1986, pp. 106-112).
 Read a review in Time magazine (19 April 1937), "Theatre: Fall of the City".
The plot centers on a radio announcer reporting from the plaza of a nameless city, where a crowd awaits the appearance of a woman who has risen from her grave for the previous three nights. She appears and predicts
The city of masterless men will take a master.
There will be shouting then: Blood after!
The first messenger brings news of a conqueror's arrival. He says those conquered live in terror. A pacifist orator argues for non-violent acceptance of the coming conqueror. Reason and appeasement and scorn will eventually conquer the conqueror, he says.
A second messenger arrives and reports the conquered peoples have embraced the conqueror. The priests of the city then advise the people of the city to "turn to your gods" and almost instigate the sacrifice of a citizen before they are interrupted by a general who calls for resistance. The citizens have already given up, however, their will broken by the hope that their loss of freedom will solve their problems or simplify their lives.
The conqueror arrives and ascends to the podium. He raises his metal visor. Only the radio announcer can see that the suit of armor is empty. He concludes
People invent their oppressors. The city is fallen.