В 1931 году в Исаакиевском соборе демонстрировали опыт с маятником Фуко

The Soviet regime was tough on religion: the experiment was scheduled for Easter night. 7,000 Leningrad residents clotted inside St. Isaac Cathedral turned into an antireligious museum. On the next day, the Red Newspaper reported: “Numerous visitors were listening to the lecture devoted to Foucault’s experiment by professor Kamenschikov with genuine interest. The lecture was radiocasted to a number of Soviet cities.” After that, Foucault’s pendulum would hang in St. Isaac Cathedral for a long time “drawing its diagonals in a vacuum, from edge to edge of stigmatically closed line,” as Umberto Eco wrote in his same-name novel.