Mostra autarchica del Minerale italiano
The Mostra autarchica del Minerale italiano (English: Autarchic Exhibition of Italian Minerals) was a propaganda exhibition held from November 1938 to May 1939 in Rome near the Circus Maximus. Spanning around 35,000 square metres (approximately 8.5 acres), the exhibition comprised 26 pavilions and attracted over a million visitors.
Source: Wikipedia — Mostra autarchica del Minerale italiano (CC BY-SA 4.0)