Carolin Mine, BC, Canada. It was an abandoned gold mine at the time. Can't go back because they decided to reactivate it. Guess gold has gone up enough since it was shut down.
Just like SHA256 miners being shut down when the price of Bitcoin drops, just to be started up again once the price rises again, same concept in practice. Interesting thing about gold-
is that the price over thousands of years have been extremely stable, it may be that more effective methods or less costly machinery has come online and made it profitable to mine.