Atocha is a mining town in Potosí, Bolivia.
Either by train from Uyuni/Oruro, or from Tupiza/Villazon, or by bus from Uyuni or Tupiza. The latter options offers much more scenery, well above 4000 m.
Just suck in the atmosphere of a genuine Bolivian mining gulch. No tourists here.
Many small eateries.
Several simple inns.