The OK-GLI was the testbed for the soviet Buran shuttle program. OK-GLI corresponded to the american "Enterprise" shuttle and had additional engines to take off under its own power during atmospheric flight testing.
The entire Buran project never really got off the ground- the only space-worthy orbiter was destroyed when its hangar caved in in 2002. Before that it completed its only orbital flight in 1988.

Museum of Technology in Speyer