In season 3 of "Stranger Things" a machine called the Key was located where?

In season 3 of "Stranger Things," the machine called the Key was located beneath Starcourt Mall. The device was part of a secret Soviet facility hidden under Hawkins’ newly opened shopping center.

The Russians built the underground base to reopen a gateway to the Upside Down. Their earlier attempt in Russia had failed, but the unusual energy conditions around Hawkins made the town a useful location. The Key generated the enormous energy needed to force open the interdimensional barrier.

Dustin, Steve, Robin, and Erica discover the facility after using a hidden elevator in the mall. Hopper and Joyce later reach the machine’s control area, where they attempt to shut the gate. The mall itself is therefore more than a setting for the season’s battles: it conceals the Soviet operation directly underneath it. Viewers sometimes confuse this gate with the original portal beneath Hawkins National Laboratory, but season 3 introduces a separate Russian installation beneath Starcourt.