Sasaune Copper Mining (吉岡銅山笹畝坑道) was found in 807. Many Sengoku Daimyo, the feudal lords fought for the right and interest of this mining. In Edoperiod, it was directly owned by Tokugawa Government.
Tourist Info.
Admission: 300 yen
Access
0. at Okayama Station.
1. use JR Hakubi Line to Bitchu Takahashi.
2. use bus to Fukiya Furusatomura.
3. use a taxi.
Better to visit by a car.
300 JPY
45 min
New Wave Samurai Movie. 
映画好き集まれ！ 
Sasaune Mining is the historic mining shaft which allows visitors to actually descend into one of the region's most important former copper mines.
The entire mining was restored as the museum of copper mining. The temperature inside of the mining is about 15c average.