As World War II approached, the city of Vilnius (Vilna in Yiddush) had a Jewish and Yiddush speaking population of about 100,00, approximately 40% of the total population of Vilnius. There were more than 200 Synagogues and smaller houses of Jewish worship and study. The Great Synagogue was the largest and most impressive of them all, having inspired Napoleon Bonaparte in 1812 to call Vilnius “The Jerusalem of the North.” The Nazis gutted the Great Synagogue and the Soviets toppled the walls. Nevertheless, much of the Great Synagogue was constructed below ground and much of the architecture and many artifacts remained. From 2015 until the present, Harry Jol from the University of Wisconsin at Eau Claire and we Calgary geophysicists have been exploring for and mapping the remains of the Great Synagogue and the associated Strashun Library. Excavations have been proceeding since 2016, and the architecture of this iconic building in the very heart of the Old City of Vilnius is slowly re-emerging.