observation post
- a post for watching the movement of enemy forces or the effect of artillery fire
Wiktionary
noun
- a lookout or vantage point
“The south polar region of Promethei Planum developed a Bermuda Triangle reputation. Satellites detected intermittent mass concentrations and magnetic field shifts. In 2148, prospectors working near Deseado Crater discovered an underground complex: a Prothean observation post. The odd phenomena were generated by the operation and discharge of a mass effect core, struggling to function despite fifty millennia of neglect.”