The Energia rocket was the most powerful rocket ever built. It could carry huge payloads (130 tons into low orbit) or the Soviet shuttle Buran (equivalent to the American shuttle).  The site 250 was dedicated to motors testing and to launches. There were two other launch sites for Energia (Site 110).  Following the collapse of the Soviet Union, the Energia rocket was abandoned after only two launches, one of which with the unmanned shuttle Buran (from Site 110).  This is where the main engines were located for testing and for the only launch that took place from this site. The ground is 60 meters under the trap !  DSCF1982  DSCF1979 mod 
DSCF1985  Our guide Vladimir Anatolyevich Polouectov, Roscosmos, site safety officer.  The site with the Energia rocket during its glorious days (photo from internet)